Section 5. Potential Flight Hazards
7-5-1. Accident Cause Factors
a. The 10 most frequent cause factors for general
aviation accidents that involve the pilot-in-command
1. Inadequate preflight preparation and/or
2. Failure to obtain and/or maintain flying
3. Failure to maintain direction control.
4. Improper level off.
5. Failure to see and avoid objects or
6. Mismanagement of fuel.
7. Improper inflight decisions or planning.
8. Misjudgment of distance and speed.
9. Selection of unsuitable terrain.
10. Improper operation of flight controls.
b. This list remains relatively stable and points out
the need for continued refresher training to establish
a higher level of flight proficiency for all pilots. A
part of the FAA's continuing effort to promote
increased aviation safety is the Aviation Safety
Program. For information on Aviation Safety
Program activities contact your nearest Flight
Standards District Office.
c. Alertness. Be alert at all times, especially
when the weather is good. Most pilots pay attention
to business when they are operating in full IFR
weather conditions, but strangely, air collisions
almost invariably have occurred under ideal weather
conditions. Unlimited visibility appears to encourage
a sense of security which is not at all justified.
Considerable information of value may be obtained
by listening to advisories being issued in the terminal
area, even though controller workload may prevent a
pilot from obtaining individual service.
d. Giving Way. If you think another aircraft is too
close to you, give way instead of waiting for the other
pilot to respect the right-of-way to which you may be
entitled. It is a lot safer to pursue the right-of-way
angle after you have completed your flight.
7-5-2. VFR in Congested Areas
A high percentage of near midair collisions occur
below 8,000 feet AGL and within 30 miles of an
airport. When operating VFR in these highly
congested areas, whether you intend to land at an
airport within the area or are just flying through, it is
recommended that extra vigilance be maintained and
that you monitor an appropriate control frequency.
Normally the appropriate frequency is an approach
control frequency. By such monitoring action you can
"get the picture" of the traffic in your area. When the
approach controller has radar, radar traffic advisories
may be given to VFR pilots upon request.
4-1-15, Radar Traffic Information Service.
7-5-3. Obstructions To Flight
a. General. Many structures exist that could
significantly affect the safety of your flight when
operating below 500 feet AGL, and particularly
below 200 feet AGL. While 14 CFR Part 91.119
allows flight below 500 AGL when over sparsely
populated areas or open water, such operations are
very dangerous. At and below 200 feet AGL there are
numerous power lines, antenna towers, etc., that are
not marked and lighted as obstructions and; therefore,
may not be seen in time to avoid a collision. Notices
to Airmen (NOTAMs) are issued on those lighted
structures experiencing temporary light outages.
However, some time may pass before the FAA is
notified of these outages, and the NOTAM issued,
thus pilot vigilance is imperative.
b. Antenna Towers. Extreme caution should be
exercised when flying less than 2,000 feet AGL
because of numerous skeletal structures, such as radio
and television antenna towers, that exceed 1,000 feet
AGL with some extending higher than 2,000 feet
AGL. Most skeletal structures are supported by guy
wires which are very difficult to see in good weather
and can be invisible at dusk or during periods of
reduced visibility. These wires can extend about
1,500 feet horizontally from a structure; therefore, all
skeletal structures should be avoided horizontally by
at least 2,000 feet. Additionally, new towers may not
be on your current chart because the information was
not received prior to the printing of the chart.
c. Overhead Wires. Overhead transmission and
utility lines often span approaches to runways,
natural flyways such as lakes, rivers, gorges, and
canyons, and cross other landmarks pilots frequently
follow such as highways, railroad tracks, etc. As with
antenna towers, these high voltage/power lines or the
supporting structures of these lines may not always be
readily visible and the wires may be virtually
impossible to see under certain conditions. In some
locations, the supporting structures of overhead
transmission lines are equipped with unique sequence
flashing white strobe light systems to indicate that
there are wires between the structures. However,
many power lines do not require notice to the FAA
and, therefore, are not marked and/or lighted. Many
of those that do require notice do not exceed 200 feet
AGL or meet the Obstruction Standard of 14 CFR
Part 77 and, therefore, are not marked and/or lighted.
All pilots are cautioned to remain extremely vigilant
for these power lines or their supporting structures
when following natural flyways or during the
approach and landing phase. This is particularly
important for seaplane and/or float equipped aircraft
when landing on, or departing from, unfamiliar lakes
d. Other Objects/Structures. There are other
objects or structures that could adversely affect your
flight such as construction cranes near an airport,
newly constructed buildings, new towers, etc. Many
of these structures do not meet charting requirements
or may not yet be charted because of the charting
cycle. Some structures do not require obstruction
marking and/or lighting and some may not be marked
and lighted even though the FAA recommended it.
7-5-4. Avoid Flight Beneath Unmanned
a. The majority of unmanned free balloons
currently being operated have, extending below
them, either a suspension device to which the payload
or instrument package is attached, or a trailing wire
antenna, or both. In many instances these balloon
subsystems may be invisible to the pilot until the
aircraft is close to the balloon, thereby creating a
potentially dangerous situation. Therefore, good
judgment on the part of the pilot dictates that aircraft
should remain well clear of all unmanned free
balloons and flight below them should be avoided at
b. Pilots are urged to report any unmanned free
balloons sighted to the nearest FAA ground facility
with which communication is established. Such
information will assist FAA ATC facilities to identify
and flight follow unmanned free balloons operating
in the airspace.
7-5-5. Unmanned Aircraft Systems
a. Unmanned Aircraft Systems (UAS), formerly
referred to as "Unmanned Aerial Vehicles" (UAVs)
or "drones," are having an increasing operational
presence in the NAS. Once the exclusive domain of
the military, UAS are now being operated by various
entities. Although these aircraft are "unmanned,"
UAS are flown by a remotely located pilot and crew.
Physical and performance characteristics of unmanned aircraft (UA) vary greatly and unlike model
aircraft that typically operate lower than 400 feet
AGL, UA may be found operating at virtually any
altitude and any speed. Sizes of UA can be as small
as several pounds to as large as a commercial
transport aircraft. UAS come in various categories
including airplane, rotorcraft, powered-lift (tilt-rotor), and lighter-than-air. Propulsion systems of
UAS include a broad range of alternatives from
piston powered and turbojet engines to battery and
solar-powered electric motors.
b. To ensure segregation of UAS operations from
other aircraft, the military typically conducts UAS
operations within restricted or other special use
airspace. However, UAS operations are now being
approved in the NAS outside of special use airspace
through the use of FAA-issued Certificates of Waiver
or Authorization (COA) or through the issuance of a
special airworthiness certificate. COA and special
airworthiness approvals authorize UAS flight
operations to be contained within specific geographic
boundaries and altitudes, usually require coordination with an ATC facility, and typically require the
issuance of a NOTAM describing the operation to be
conducted. UAS approvals also require observers to
provide "see-and-avoid" capability to the UAS crew
and to provide the necessary compliance with 14 CFR
Section 91.113. For UAS operations approved at or
above FL180, UAS operate under the same
requirements as that of manned aircraft (i.e., flights
are operated under instrument flight rules, are in
communication with ATC, and are appropriately
c. UAS operations may be approved at either
controlled or uncontrolled airports and are typically
disseminated by NOTAM. In all cases, approved
UAS operations must comply with all applicable
regulations and/or special provisions specified in the
COA or in the operating limitations of the special
airworthiness certificate. At uncontrolled airports,
UAS operations are advised to operate well clear of
all known manned aircraft operations. Pilots of
manned aircraft are advised to follow normal
operating procedures and are urged to monitor the
CTAF for any potential UAS activity. At controlled
airports, local ATC procedures may be in place to
handle UAS operations and should not require any
special procedures from manned aircraft entering or
departing the traffic pattern or operating in the
vicinity of the airport.
d. In addition to approved UAS operations
described above, a recently approved agreement
between the FAA and the Department of Defense
authorizes small UAS operations wholly contained
within Class G airspace, and in no instance, greater
than 1200 feet AGL over military owned or leased
property. These operations do not require any special
authorization as long as the UA remains within the
lateral boundaries of the military installation as well
as other provisions including the issuance of a
NOTAM. Unlike special use airspace, these areas
may not be depicted on an aeronautical chart.
e. There are several factors a pilot should consider
regarding UAS activity in an effort to reduce
potential flight hazards. Pilots are urged to exercise
increased vigilance when operating in the vicinity of
restricted or other special use airspace, military
operations areas, and any military installation. Areas
with a preponderance of UAS activity are typically
noted on sectional charts advising pilots of this
activity. Since the size of a UA can be very small, they
may be difficult to see and track. If a UA is
encountered during flight, as with manned aircraft,
never assume that the pilot or crew of the UAS can see
you, maintain increased vigilance with the UA and
always be prepared for evasive action if necessary.
Always check NOTAMs for potential UAS activity
along the intended route of flight and exercise
increased vigilance in areas specified in the NOTAM.
7-5-6. Mountain Flying
a. Your first experience of flying over mountainous terrain (particularly if most of your flight time has
been over the flatlands of the midwest) could be a
never-to-be-forgotten nightmare if proper planning is
not done and if you are not aware of the potential
hazards awaiting. Those familiar section lines are not
present in the mountains; those flat, level fields for
forced landings are practically nonexistent; abrupt
changes in wind direction and velocity occur; severe
updrafts and downdrafts are common, particularly
near or above abrupt changes of terrain such as cliffs
or rugged areas; even the clouds look different and
can build up with startling rapidity. Mountain flying
need not be hazardous if you follow the recommendations below.
b. File a Flight Plan. Plan your route to avoid
topography which would prevent a safe forced
landing. The route should be over populated areas and
well known mountain passes. Sufficient altitude
should be maintained to permit gliding to a safe
landing in the event of engine failure.
c. Don't fly a light aircraft when the winds aloft, at
your proposed altitude, exceed 35 miles per hour.
Expect the winds to be of much greater velocity over
mountain passes than reported a few miles from them.
Approach mountain passes with as much altitude as
possible. Downdrafts of from 1,500 to 2,000 feet per
minute are not uncommon on the leeward side.
d. Don't fly near or above abrupt changes in
terrain. Severe turbulence can be expected, especially
in high wind conditions.
e. Understand Mountain Obscuration. The
term Mountain Obscuration (MTOS) is used to
describe a visibility condition that is distinguished
from IFR because ceilings, by definition, are
described as "above ground level" (AGL). In
mountainous terrain clouds can form at altitudes
significantly higher than the weather reporting
station and at the same time nearby mountaintops
may be obscured by low visibility. In these areas the
ground level can also vary greatly over a small area.
Beware if operating VFR-on-top. You could be
operating closer to the terrain than you think because
the tops of mountains are hidden in a cloud deck
below. MTOS areas are identified daily on The
Aviation Weather Center located at:
f. Some canyons run into a dead end. Don't fly so
far up a canyon that you get trapped. ALWAYS BE
ABLE TO MAKE A 180 DEGREE TURN!
g. VFR flight operations may be conducted at
night in mountainous terrain with the application of
sound judgment and common sense. Proper pre-flight
planning, giving ample consideration to winds and
weather, knowledge of the terrain and pilot
experience in mountain flying are prerequisites for
safety of flight. Continuous visual contact with the
surface and obstructions is a major concern and flight
operations under an overcast or in the vicinity of
clouds should be approached with extreme caution.
h. When landing at a high altitude field, the same
indicated airspeed should be used as at low elevation
fields. Remember: that due to the less dense air at
altitude, this same indicated airspeed actually results
in higher true airspeed, a faster landing speed, and
more important, a longer landing distance. During
gusty wind conditions which often prevail at high
altitude fields, a power approach and power landing
is recommended. Additionally, due to the faster
groundspeed, your takeoff distance will increase
considerably over that required at low altitudes.
i. Effects of Density Altitude. Performance
figures in the aircraft owner's handbook for length of
takeoff run, horsepower, rate of climb, etc., are
generally based on standard atmosphere conditions
(59 degrees Fahrenheit (15 degrees Celsius), pressure
29.92 inches of mercury) at sea level. However,
inexperienced pilots, as well as experienced pilots,
may run into trouble when they encounter an
altogether different set of conditions. This is
particularly true in hot weather and at higher
elevations. Aircraft operations at altitudes above sea
level and at higher than standard temperatures are
commonplace in mountainous areas. Such operations
quite often result in a drastic reduction of aircraft
performance capabilities because of the changing air
density. Density altitude is a measure of air density.
It is not to be confused with pressure altitude, true
altitude or absolute altitude. It is not to be used as a
height reference, but as a determining criteria in the
performance capability of an aircraft. Air density
decreases with altitude. As air density decreases,
density altitude increases. The further effects of high
temperature and high humidity are cumulative,
resulting in an increasing high density altitude
condition. High density altitude reduces all aircraft
performance parameters. To the pilot, this means that
the normal horsepower output is reduced, propeller
efficiency is reduced and a higher true airspeed is
required to sustain the aircraft throughout its
operating parameters. It means an increase in runway
length requirements for takeoff and landings, and
decreased rate of climb. An average small airplane,
for example, requiring 1,000 feet for takeoff at sea
level under standard atmospheric conditions will
require a takeoff run of approximately 2,000 feet at an
operational altitude of 5,000 feet.
A turbo-charged aircraft engine provides some slight
advantage in that it provides sea level horsepower up to a
specified altitude above sea level.
1. Density Altitude Advisories. At airports
with elevations of 2,000 feet and higher, control
towers and FSSs will broadcast the advisory "Check
Density Altitude" when the temperature reaches a
predetermined level. These advisories will be
broadcast on appropriate tower frequencies or, where
available, ATIS. FSSs will broadcast these advisories
as a part of Local Airport Advisory, and on TWEB.
2. These advisories are provided by air traffic
facilities, as a reminder to pilots that high
temperatures and high field elevations will cause
significant changes in aircraft characteristics. The
pilot retains the responsibility to compute density
altitude, when appropriate, as a part of preflight
All FSSs will compute the current density altitude upon
j. Mountain Wave. Many pilots go all their lives
without understanding what a mountain wave is.
Quite a few have lost their lives because of this lack
of understanding. One need not be a licensed
meteorologist to understand the mountain wave
1. Mountain waves occur when air is being
blown over a mountain range or even the ridge of a
sharp bluff area. As the air hits the upwind side of the
range, it starts to climb, thus creating what is
generally a smooth updraft which turns into a
turbulent downdraft as the air passes the crest of the
ridge. From this point, for many miles downwind,
there will be a series of downdrafts and updrafts.
Satellite photos of the Rockies have shown mountain
waves extending as far as 700 miles downwind of the
range. Along the east coast area, such photos of the
Appalachian chain have picked up the mountain
wave phenomenon over a hundred miles eastward.
All it takes to form a mountain wave is wind blowing
across the range at 15 knots or better at an intersection
angle of not less than 30 degrees.
2. Pilots from flatland areas should understand
a few things about mountain waves in order to stay
out of trouble. When approaching a mountain range
from the upwind side (generally the west), there will
usually be a smooth updraft; therefore, it is not quite
as dangerous an area as the lee of the range. From the
leeward side, it is always a good idea to add an extra
thousand feet or so of altitude because downdrafts
can exceed the climb capability of the aircraft. Never
expect an updraft when approaching a mountain
chain from the leeward. Always be prepared to cope
with a downdraft and turbulence.
3. When approaching a mountain ridge from the
downwind side, it is recommended that the ridge be
approached at approximately a 45 degree angle to the
horizontal direction of the ridge. This permits a safer
retreat from the ridge with less stress on the aircraft
should severe turbulence and downdraft be experienced. If severe turbulence is encountered,
simultaneously reduce power and adjust pitch until
aircraft approaches maneuvering speed, then adjust
power and trim to maintain maneuvering speed and
fly away from the turbulent area.
7-5-7. Use of Runway Half-way Signs at
When installed, runway half-way signs provide the
pilot with a reference point to judge takeoff
acceleration trends. Assuming that the runway length
is appropriate for takeoff (considering runway
condition and slope, elevation, aircraft weight, wind,
and temperature), typical takeoff acceleration should
allow the airplane to reach 70 percent of lift-off
airspeed by the midpoint of the runway. The "rule of
thumb" is that should airplane acceleration not allow
the airspeed to reach this value by the midpoint, the
takeoff should be aborted, as it may not be possible to
liftoff in the remaining runway.
Several points are important when considering using
this "rule of thumb":
a. Airspeed indicators in small airplanes are not
required to be evaluated at speeds below stalling, and
may not be usable at 70 percent of liftoff airspeed.
b. This "rule of thumb" is based on a uniform
surface condition. Puddles, soft spots, areas of tall
and/or wet grass, loose gravel, etc., may impede
acceleration or even cause deceleration. Even if the
airplane achieves 70 percent of liftoff airspeed by the
midpoint, the condition of the remainder of the runway
may not allow further acceleration. The entire length
of the runway should be inspected prior to takeoff to
ensure a usable surface.
c. This "rule of thumb" applies only to runway
required for actual liftoff. In the event that obstacles
affect the takeoff climb path, appropriate distance
must be available after liftoff to accelerate to best angle
of climb speed and to clear the obstacles. This will, in
effect, require the airplane to accelerate to a higher
speed by midpoint, particularly if the obstacles are
close to the end of the runway. In addition, this
technique does not take into account the effects of
upslope or tailwinds on takeoff performance. These
factors will also require greater acceleration than
normal and, under some circumstances, prevent
d. Use of this "rule of thumb" does not alleviate the
pilot's responsibility to comply with applicable
Federal Aviation Regulations, the limitations and
performance data provided in the FAA approved
Airplane Flight Manual (AFM), or, in the absence of
an FAA approved AFM, other data provided by the
In addition to their use during takeoff, runway
half-way signs offer the pilot increased awareness of
his or her position along the runway during landing
No FAA standard exists for the appearance of the runway
half-way sign. FIG 7-5-1 shows a graphical depiction of
a typical runway half-way sign.
7-5-8. Seaplane Safety
a. Acquiring a seaplane class rating affords access
to many areas not available to landplane pilots.
Adding a seaplane class rating to your pilot certificate
can be relatively uncomplicated and inexpensive.
However, more effort is required to become a safe,
efficient, competent "bush" pilot. The natural hazards
of the backwoods have given way to modern
man-made hazards. Except for the far north, the
available bodies of water are no longer the exclusive
domain of the airman. Seaplane pilots must be
vigilant for hazards such as electric power lines,
power, sail and rowboats, rafts, mooring lines, water
skiers, swimmers, etc.
Typical Runway Half-way Sign
b. Seaplane pilots must have a thorough understanding of the right-of-way rules as they apply to
aircraft versus other vessels. Seaplane pilots are
expected to know and adhere to both the U.S. Coast
Guard's (USCG) Navigation Rules, International-Inland, and 14 CFR Section 91.115, Right-of-Way
Rules; Water Operations. The navigation rules of the
road are a set of collision avoidance rules as they
apply to aircraft on the water. A seaplane is
considered a vessel when on the water for the
purposes of these collision avoidance rules. In
general, a seaplane on the water must keep well clear
of all vessels and avoid impeding their navigation.
The CFR requires, in part, that aircraft operating on
the water ". . . shall, insofar as possible, keep clear of
all vessels and avoid impeding their navigation, and
shall give way to any vessel or other aircraft that is
given the right-of-way . . . ." This means that a
seaplane should avoid boats and commercial
shipping when on the water. If on a collision course,
the seaplane should slow, stop, or maneuver to the
right, away from the bow of the oncoming vessel.
Also, while on the surface with an engine running, an
aircraft must give way to all nonpowered vessels.
Since a seaplane in the water may not be as
maneuverable as one in the air, the aircraft on the
water has right-of-way over one in the air, and one
taking off has right-of-way over one landing. A
seaplane is exempt from the USCG safety equipment
requirements, including the requirements for Personal Flotation Devices (PFD). Requiring seaplanes on
the water to comply with USCG equipment
requirements in addition to the FAA equipment
requirements would be an unnecessary burden on
seaplane owners and operators.
c. Unless they are under Federal jurisdiction,
navigable bodies of water are under the jurisdiction
of the state, or in a few cases, privately owned. Unless
they are specifically restricted, aircraft have as much
right to operate on these bodies of water as other
vessels. To avoid problems, check with Federal or
local officials in advance of operating on unfamiliar
waters. In addition to the agencies listed in
TBL 7-5-1, the nearest Flight Standards District
Office can usually offer some practical suggestions as
well as regulatory information. If you land on a
restricted body of water because of an inflight
emergency, or in ignorance of the restrictions you
have violated, report as quickly as practical to the
nearest local official having jurisdiction and explain
d. When operating a seaplane over or into remote
areas, appropriate attention should be given to
survival gear. Minimum kits are recommended for
summer and winter, and are required by law for flight
into sparsely settled areas of Canada and Alaska.
Alaska State Department of Transportation and
Canadian Ministry of Transport officials can provide
specific information on survival gear requirements.
The kit should be assembled in one container and be
easily reachable and preferably floatable.
Jurisdictions Controlling Navigable Bodies of Water
Authority to Consult For Use of a Body of Water
Local forest ranger
Local forest ranger
of the Interior,
Local park ranger
USDI, Bureau of
or state forestry or
aviation office for
restricted on an
from province to
province and by
departments of the
e. The FAA recommends that each seaplane owner
or operator provide flotation gear for occupants any
time a seaplane operates on or near water. 14 CFR
Section 91.205(b)(12) requires approved flotation
gear for aircraft operated for hire over water and
beyond power-off gliding distance from shore.
FAA-approved gear differs from that required for
navigable waterways under USCG rules. FAA-approved life vests are inflatable designs as compared
to the USCG's noninflatable PFD's that may consist
of solid, bulky material. Such USCG PFDs are
impractical for seaplanes and other aircraft because
they may block passage through the relatively narrow
exits available to pilots and passengers. Life vests
approved under Technical Standard Order (TSO)
TSO-C13E contain fully inflatable compartments.
The wearer inflates the compartments (AFTER
exiting the aircraft) primarily by independent CO2
cartridges, with an oral inflation tube as a backup. The
flotation gear also contains a water-activated,
self-illuminating signal light. The fact that pilots and
passengers can easily don and wear inflatable life
vests (when not inflated) provides maximum
effectiveness and allows for unrestricted movement.
It is imperative that passengers are briefed on the
location and proper use of available PFDs prior to
leaving the dock.
f. The FAA recommends that seaplane owners and
operators obtain Advisory Circular (AC) 91-69,
Seaplane Safety for 14 CFR Part 91 Operations, free
from the U.S. Department of Transportation,
Subsequent Distribution Office, SVC-121.23, Ardmore East Business Center, 3341 Q 75th Avenue,
Landover, MD 20785; fax: (301) 386-5394. The
USCG Navigation Rules International-Inland
(COMDTINSTM 16672.2B) is available for a fee
from the Government Printing Office by facsimile
request to (202) 512-2250, and can be ordered using
Mastercard or Visa.
7-5-9. Flight Operations in Volcanic Ash
volcanic eruptions which send ash and sulphur dioxide (SO2) gas into
the upper atmosphere occur somewhere around the world several times each year.
Flying into a volcanic ash cloud can be exceedingly dangerous. A B747-200 lost
all four engines after such an encounter and a B747-400 had the same nearly
catastrophic experience. Piston-powered aircraft are less likely to lose power
but severe damage is almost certain to ensue after an encounter with a volcanic
ash cloud which is only a few hours old.
important is to avoid any encounter with volcanic ash. The ash plume may not be
visible, especially in instrument conditions or at night; and even if visible,
it is difficult to distinguish visually between an ash cloud and an ordinary
weather cloud. Volcanic ash clouds are not displayed on airborne or ATC radar.
The pilot must rely on reports from air traffic controllers and other pilots to
determine the location of the ash cloud and use that information to remain well
clear of the area. Additionally, the presence of a sulphur-like odor throughout
the cabin may indicate the presence of SO2 emitted by volcanic
activity, but may or may not indicate the presence of volcanic ash. Every
attempt should be made to remain on the upwind side of the volcano.
c. It is recommended that pilots encountering an
ash cloud should immediately reduce thrust to idle
(altitude permitting), and reverse course in order to
escape from the cloud. Ash clouds may extend for
hundreds of miles and pilots should not attempt to fly
through or climb out of the cloud. In addition, the
following procedures are recommended:
1. Disengage the autothrottle if engaged. This
will prevent the autothrottle from increasing engine
2. Turn on continuous ignition;
3. Turn on all accessory airbleeds including all
air conditioning packs, nacelles, and wing anti-ice.
This will provide an additional engine stall margin by
reducing engine pressure.
d. The following has been reported by flightcrews
who have experienced encounters with volcanic dust
1. Smoke or dust appearing in the cockpit.
2. An acrid odor similar to electrical smoke.
3. Multiple engine malfunctions, such as
compressor stalls, increasing EGT, torching from
tailpipe, and flameouts.
4. At night, St. Elmo's fire or other static
discharges accompanied by a bright orange glow in
the engine inlets.
5. A fire warning in the forward cargo area.
e. It may become necessary to shut down and then
restart engines to prevent exceeding EGT limits.
Volcanic ash may block the pitot system and result in
unreliable airspeed indications.
f. If you see a volcanic eruption and have not been
previously notified of it, you may have been the first
person to observe it. In this case, immediately contact
ATC and alert them to the existence of the eruption.
If possible, use the Volcanic Activity Reporting form
(VAR) depicted in Appendix 2 of this
manual. Items 1 through 8 of the VAR should be
transmitted immediately. The information requested
in items 9 through 16 should be passed after landing.
If a VAR form is not immediately available, relay
enough information to identify the position and
nature of the volcanic activity. Do not become
unnecessarily alarmed if there is merely steam or very
low-level eruptions of ash.
g. When landing at airports where volcanic ash has
been deposited on the runway, be aware that even a
thin layer of dry ash can be detrimental to braking
action. Wet ash on the runway may also reduce
effectiveness of braking. It is recommended that
reverse thrust be limited to minimum practical to
reduce the possibility of reduced visibility and engine
ingestion of airborne ash.
h. When departing from airports where volcanic
ash has been deposited, it is recommended that pilots
avoid operating in visible airborne ash. Allow ash to
settle before initiating takeoff roll. It is also
recommended that flap extension be delayed until
initiating the before takeoff checklist and that a
rolling takeoff be executed to avoid blowing ash back
into the air.
7-5-10. Emergency Airborne Inspection of
a. Providing airborne assistance to another aircraft
may involve flying in very close proximity to that
aircraft. Most pilots receive little, if any, formal
training or instruction in this type of flying activity.
Close proximity flying without sufficient time to plan
(i.e., in an emergency situation), coupled with the
stress involved in a perceived emergency can be
b. The pilot in the best position to assess the
situation should take the responsibility of coordinating the airborne intercept and inspection, and take
into account the unique flight characteristics and
differences of the category(s) of aircraft involved.
c. Some of the safety considerations are:
1. Area, direction and speed of the intercept;
2. Aerodynamic effects (i.e., rotorcraft downwash);
3. Minimum safe separation distances;
4. Communications requirements, lost communications procedures, coordination with ATC;
5. Suitability of diverting the distressed aircraft
to the nearest safe airport; and
6. Emergency actions to terminate the intercept.
d. Close proximity, inflight inspection of another
aircraft is uniquely hazardous. The pilot-in-command of the aircraft experiencing the
problem/emergency must not relinquish control of
the situation and/or jeopardize the safety of their
aircraft. The maneuver must be accomplished with
minimum risk to both aircraft.
7-5-11. Precipitation Static
a. Precipitation static is caused by aircraft in flight
coming in contact with uncharged particles. These
particles can be rain, snow, fog, sleet, hail, volcanic
ash, dust; any solid or liquid particles. When the
aircraft strikes these neutral particles the positive
element of the particle is reflected away from the
aircraft and the negative particle adheres to the skin
of the aircraft. In a very short period of time a
substantial negative charge will develop on the skin
of the aircraft. If the aircraft is not equipped with
static dischargers, or has an ineffective static
discharger system, when a sufficient negative voltage
level is reached, the aircraft may go into
"CORONA." That is, it will discharge the static
electricity from the extremities of the aircraft, such as
the wing tips, horizontal stabilizer, vertical stabilizer,
antenna, propeller tips, etc. This discharge of static
electricity is what you will hear in your headphones
and is what we call P-static.
b. A review of pilot reports often shows different
symptoms with each problem that is encountered.
The following list of problems is a summary of many
pilot reports from many different aircraft. Each
problem was caused by P-static:
1. Complete loss of VHF communications.
2. Erroneous magnetic compass readings
(30 percent in error).
3. High pitched squeal on audio.
4. Motor boat sound on audio.
5. Loss of all avionics in clouds.
6. VLF navigation system inoperative most of
7. Erratic instrument readouts.
8. Weak transmissions and poor receptivity of
9. "St. Elmo's Fire" on windshield.
c. Each of these symptoms is caused by one
general problem on the airframe. This problem is the
inability of the accumulated charge to flow easily to
the wing tips and tail of the airframe, and properly
discharge to the airstream.
d. Static dischargers work on the principal of
creating a relatively easy path for discharging
negative charges that develop on the aircraft by using
a discharger with fine metal points, carbon coated
rods, or carbon wicks rather than wait until a large
charge is developed and discharged off the trailing
edges of the aircraft that will interfere with avionics
equipment. This process offers approximately
50 decibels (dB) static noise reduction which is
adequate in most cases to be below the threshold of
noise that would cause interference in avionics
e. It is important to remember that precipitation
static problems can only be corrected with the proper
number of quality static dischargers, properly
installed on a properly bonded aircraft. P-static is
indeed a problem in the all weather operation of the
aircraft, but there are effective ways to combat it. All
possible methods of reducing the effects of P-static
should be considered so as to provide the best
possible performance in the flight environment.
f. A wide variety of discharger designs is available
on the commercial market. The inclusion of
well-designed dischargers may be expected to
improve airframe noise in P-static conditions by as
much as 50 dB. Essentially, the discharger provides
a path by which accumulated charge may leave the
airframe quietly. This is generally accomplished by
providing a group of tiny corona points to permit
onset of corona-current flow at a low aircraft
potential. Additionally, aerodynamic design of
dischargers to permit corona to occur at the lowest
possible atmospheric pressure also lowers the corona
threshold. In addition to permitting a low-potential
discharge, the discharger will minimize the radiation
of radio frequency (RF) energy which accompanies
the corona discharge, in order to minimize effects of
RF components at communications and navigation
frequencies on avionics performance. These effects
are reduced through resistive attachment of the
corona point(s) to the airframe, preserving direct
current connection but attenuating the higher-frequency components of the discharge.
g. Each manufacturer of static dischargers offers
information concerning appropriate discharger location on specific airframes. Such locations emphasize
the trailing outboard surfaces of wings and horizontal
tail surfaces, plus the tip of the vertical stabilizer,
where charge tends to accumulate on the airframe.
Sufficient dischargers must be provided to allow for
current-carrying capacity which will maintain
airframe potential below the corona threshold of the
h. In order to achieve full performance of avionic
equipment, the static discharge system will require
periodic maintenance. A pilot knowledgeable of
P-static causes and effects is an important element in
assuring optimum performance by early recognition
of these types of problems.
7-5-12. Light Amplification by Stimulated
Emission of Radiation (Laser) Operations
and Reporting Illumination of Aircraft
a. Lasers have many applications. Of concern to
users of the National Airspace System are those laser
events that may affect pilots, e.g., outdoor laser light
shows or demonstrations for entertainment and
advertisements at special events and theme parks.
Generally, the beams from these events appear as
bright blue-green in color; however, they may be red,
yellow, or white. However, some laser systems
produce light which is invisible to the human eye.
b. FAA regulations prohibit the disruption of
aviation activity by any person on the ground or in the
air. The FAA and the Food and Drug Administration
(the Federal agency that has the responsibility to
enforce compliance with Federal requirements for
laser systems and laser light show products) are
working together to ensure that operators of these
devices do not pose a hazard to aircraft operators.
c. Pilots should be aware that illumination from
these laser operations are able to create temporary
vision impairment miles from the actual location. In
addition, these operations can produce permanent eye
damage. Pilots should make themselves aware of
where these activities are being conducted and avoid
these areas if possible.
d. Recent and increasing incidents of unauthorized illumination of aircraft by lasers, as well as the
proliferation and increasing sophistication of laser
devices available to the general public, dictates that
the FAA, in coordination with other government
agencies, take action to safeguard flights from these
e. Pilots should report laser illumination activity to
the controlling Air Traffic Control facilities, Federal
Contract Towers or Flight Service Stations as soon as
possible after the event. The following information
should be included:
1. UTC Date and Time of Event.
2. Call Sign or Aircraft Registration Number.
3. Type Aircraft.
4. Nearest Major City.
6. Location of Event (Latitude/Longitude and/or Fixed Radial Distance (FRD)).
7. Brief Description of the Event and any other
are also encouraged to complete the Laser Beam Exposure Questionnaire located
on the FAA Laser Safety Initiative website at
and submit electronically per the directions on the questionnaire, as soon as
possible after landing.
g. When a laser event is reported to an air traffic
facility, a general caution warning will be broadcasted on all appropriate frequencies every
five minutes for 20 minutes and broadcasted on the
ATIS for one hour following the report.
UNAUTHORIZED LASER ILLUMINATION EVENT,
(UTC time), (location), (altitude), (color), (direction).
"Unauthorized laser illumination event, at 0100z, 8 mile final runway 18R at
3,000 feet, green laser from the southwest."
FAAO 7110.65, Unauthorized Laser Illumination of Aircraft,
FAAO 7210.3, Reporting Laser Illumination of Aircraft, Para 2-1-27.
h. When these activities become known to the
FAA, Notices to Airmen (NOTAMs) are issued to
inform the aviation community of the events. Pilots
should consult NOTAMs or the Special Notices
section of the Airport/Facility Directory for information regarding these activities.
7-5-13. Flying in Flat Light and White Out
a. Flat Light. Flat
light is an optical illusion, also known as "sector or partial white out." It is not as
severe as "white out" but the condition causes pilots
to lose their depth-of-field and contrast in vision.
Flat light conditions are usually accompanied by
overcast skies inhibiting any visual clues. Such
conditions can occur anywhere in the world,
primarily in snow covered areas but can occur in dust,
sand, mud flats, or on glassy water. Flat light can
completely obscure features of the terrain, creating an
inability to distinguish distances and closure rates.
As a result of this reflected light, it can give pilots the
illusion that they are ascending or descending when
they may actually be flying level. However, with
good judgment and proper training and planning, it is
possible to safely operate an aircraft in flat light
b. White Out. As defined in meteorological
terms, white out occurs when a person becomes
engulfed in a uniformly white glow. The glow is a
result of being surrounded by blowing snow, dust,
sand, mud or water. There are no shadows, no horizon
or clouds and all depth-of-field and orientation are
lost. A white out situation is severe in that there are
no visual references. Flying is not recommended in
any white out situation. Flat light conditions can lead
to a white out environment quite rapidly, and both
atmospheric conditions are insidious; they sneak up
on you as your visual references slowly begin to
disappear. White out has been the cause of several
c. Self Induced White Out. This effect typically
occurs when a helicopter takes off or lands on a
snow-covered area. The rotor down wash picks up
particles and re-circulates them through the rotor
down wash. The effect can vary in intensity
depending upon the amount of light on the surface.
This can happen on the sunniest, brightest day with
good contrast everywhere. However, when it
happens, there can be a complete loss of visual clues.
If the pilot has not prepared for this immediate loss of
visibility, the results can be disastrous. Good
planning does not prevent one from encountering flat
light or white out conditions.
d. Never take off in a white out situation.
1. Realize that in flat light conditions it may be
possible to depart but not to return to that site. During
takeoff, make sure you have a reference point. Do not
lose sight of it until you have a departure reference
point in view. Be prepared to return to the takeoff
reference if the departure reference does not come
2. Flat light is common to snow skiers. One way
to compensate for the lack of visual contrast and
depth-of-field loss is by wearing amber tinted lenses
(also known as blue blockers). Special note of
caution: Eyewear is not ideal for every pilot. Take
into consideration personal factors - age, light
sensitivity, and ambient lighting conditions.
3. So what should a pilot do when all visual
references are lost?
(a) Trust the cockpit instruments.
(b) Execute a 180 degree turnaround and start
looking for outside references.
(c) Above all - fly the aircraft.
e. Landing in Low Light Conditions. When
landing in a low light condition - use extreme
caution. Look for intermediate reference points, in
addition to checkpoints along each leg of the route for
course confirmation and timing. The lower the
ambient light becomes, the more reference points a
pilot should use.
f. Airport Landings.
1. Look for features around the airport or
approach path that can be used in determining depth
perception. Buildings, towers, vehicles or other
aircraft serve well for this measurement. Use
something that will provide you with a sense of height
above the ground, in addition to orienting you to the
2. Be cautious of snowdrifts and snow banks -
anything that can distinguish the edge of the runway.
Look for subtle changes in snow texture or shading to
identify ridges or changes in snow depth.
g. Off-Airport Landings.
1. In the event of an off-airport landing, pilots
have used a number of different visual cues to gain
reference. Use whatever you must to create the
contrast you need. Natural references seem to work
best (trees, rocks, snow ribs, etc.)
(a) Over flight.
(b) Use of markers.
(c) Weighted flags.
(d) Smoke bombs.
(e) Any colored rags.
(f) Dye markers.
(h) Trees or tree branches.
2. It is difficult to determine the depth of snow
in areas that are level. Dropping items from the
aircraft to use as reference points should be used as a
visual aid only and not as a primary landing reference.
Unless your marker is biodegradable, be sure to
retrieve it after landing. Never put yourself in a
position where no visual references exist.
3. Abort landing if blowing snow obscures your
reference. Make your decisions early. Don't assume
you can pick up a lost reference point when you get
4. Exercise extreme caution when flying from
sunlight into shade. Physical awareness may tell you
that you are flying straight but you may actually be in
a spiral dive with centrifugal force pressing against
you. Having no visual references enhances this
illusion. Just because you have a good visual
reference does not mean that it's safe to continue.
There may be snow-covered terrain not visible in the
direction that you are traveling. Getting caught in a no
visual reference situation can be fatal.
h. Flying Around a Lake.
1. When flying along lakeshores, use them as a
reference point. Even if you can see the other side,
realize that your depth perception may be poor. It is
easy to fly into the surface. If you must cross the lake,
check the altimeter frequently and maintain a safe
altitude while you still have a good reference. Don't
descend below that altitude.
2. The same rules apply to seemingly flat areas
of snow. If you don't have good references, avoid
i. Other Traffic. Be on the look out for other
traffic in the area. Other aircraft may be using your
same reference point. Chances are greater of
colliding with someone traveling in the same
direction as you, than someone flying in the opposite
j. Ceilings. Low ceilings have caught many pilots
off guard. Clouds do not always form parallel to the
surface, or at the same altitude. Pilots may try to
compensate for this by flying with a slight bank and
thus creating a descending turn.
k. Glaciers. Be conscious of your altitude when
flying over glaciers. The glaciers may be rising faster
than you are climbing.
7-5-14. Operations in Ground Icing
a. The presence of aircraft airframe icing during
takeoff, typically caused by improper or no deicing of
the aircraft being accomplished prior to flight has
contributed to many recent accidents in turbine
aircraft. The General Aviation Joint Steering
Committee (GAJSC) is the primary vehicle for
government-industry cooperation, communication,
and coordination on GA accident mitigation. The
Turbine Aircraft Operations Subgroup (TAOS)
works to mitigate accidents in turbine accident
aviation. While there is sufficient information and
guidance currently available regarding the effects of
icing on aircraft and methods for deicing, the TAOS
has developed a list of recommended actions to
further assist pilots and operators in this area.
While the efforts of the TAOS specifically focus on
turbine aircraft, it is recognized that their recommendations are applicable to and can be adapted for the
pilot of a small, piston powered aircraft too.
b. The following recommendations are offered:
1. Ensure that your aircraft's lift-generating
surfaces are COMPLETELY free of contamination
before flight through a tactile (hands on) check of the
critical surfaces when feasible. Even when otherwise
permitted, operators should avoid smooth or polished
frost on lift-generating surfaces as an acceptable
2. Review and refresh your cold weather
standard operating procedures.
3. Review and be familiar with the Airplane
Flight Manual (AFM) limitations and procedures
necessary to deal with icing conditions prior to flight,
as well as in flight.
4. Protect your aircraft while on the ground, if
possible, from sleet and freezing rain by taking
advantage of aircraft hangars.
5. Take full advantage of the opportunities
available at airports for deicing. Do not refuse deicing
services simply because of cost.
6. Always consider canceling or delaying a
flight if weather conditions do not support a safe
c. If you haven't already developed a set of
Standard Operating Procedures for cold weather
operations, they should include:
1. Procedures based on information that is
applicable to the aircraft operated, such as AFM
limitations and procedures;
2. Concise and easy to understand guidance that
outlines best operational practices;
3. A systematic procedure for recognizing,
evaluating and addressing the associated icing risk,
and offer clear guidance to mitigate this risk;
4. An aid (such as a checklist or reference cards)
that is readily available during normal day-to-day
d. There are several sources for guidance relating
to airframe icing, including:
4. Advisory Circular (AC) 91-74, Pilot Guide,
Flight in Icing Conditions.
5. AC 135-17, Pilot Guide Small Aircraft
6. AC 135-9, FAR Part 135 Icing Limitations.
7. AC 120-60, Ground Deicing and Anti-icing
8. AC 135-16, Ground Deicing and Anti-icing
Training and Checking.
The FAA Approved Deicing Program Updates is
published annually as a Flight Standards Information
Bulletin for Air Transportation and contains detailed
information on deicing and anti-icing procedures and
holdover times. It may be accessed at the following
web site by selecting the current year's information
7-5-15. Avoid Flight in the Vicinity of
Exhaust Plumes (Smoke Stacks and
a. Flight Hazards Exist
Around Exhaust Plumes. Exhaust plumes are defined as
visible or invisible emissions from power plants, industrial production
facilities, or other industrial systems that release large amounts of vertically
directed unstable gases (effluent). High temperature exhaust plumes can cause
significant air disturbances such as turbulence and vertical shear. Other
identified potential hazards include, but are not necessarily limited to:
reduced visibility, oxygen depletion, engine particulate contamination, exposure
to gaseous oxides, and/or icing. Results of encountering a plume may include
airframe damage, aircraft upset, and/or engine damage/failure. These hazards are
most critical during low altitude flight in calm and cold air, especially in and
around approach and departure corridors or airport traffic areas.
Whether plumes are visible or invisible, the total extent of their turbulent
affect is difficult to predict. Some studies do predict that the significant
turbulent effects of an exhaust plume can extend to heights of over 1,000 feet
above the height of the top of the stack or cooling tower. Any effects will be
more pronounced in calm stable air where the plume is very hot and the
surrounding area is still and cold. Fortunately, studies also predict that any
amount of crosswind will help to dissipate the effects. However, the size of the
tower or stack is not a good indicator of the predicted effect the plume may
produce. The major effects are related to the heat or size of the plume
effluent, the ambient air temperature, and the wind speed affecting the plume.
Smaller aircraft can expect to feel an effect at a higher altitude than heavier
b. When able, a pilot
should steer clear of exhaust plumes by flying on the upwind side of smokestacks
or cooling towers. When a plume is visible via smoke
or a condensation cloud, remain clear and realize a plume may have both visible
and invisible characteristics. Exhaust stacks without visible plumes may still
be in full operation, and airspace in the vicinity should be treated with
caution. As with mountain wave turbulence or clear air turbulence, an invisible
plume may be encountered unexpectedly. Cooling towers, power plant stacks,
exhaust fans, and other similar structures are depicted in
Pilots are encouraged to
exercise caution when flying in the vicinity of exhaust plumes. Pilots are also
encouraged to reference the Airport/Facility Directory where amplifying notes
may caution pilots and identify the location of structure(s) emitting exhaust
The best available information on this
phenomenon must come from pilots via the PIREP reporting procedures. All pilots
encountering hazardous plume conditions are urgently requested to report time,
location, and intensity (light, moderate, severe, or extreme) of the element to
the FAA facility with which they are maintaining radio contact. If time and
conditions permit, elements should be reported according to the standards for
other PIREPs and position reports (see Paragraph 7-1-23, PIREPS Relating to Turbulence).