U.S. Department

of Transportation


Federal Aviation



Air Traffic


A Communication from the  Director of Air Traffic                        



Issue # 2003-3

August 2003                                                                                             

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In this Issue:


The Importance of PIREPs
Radio Communications
Prevailing Visibility
Delay Reporting
Discretionary Descent
MSAW Safety Alert Clarification
FAQs about EDCTs associated with a GDP
Use of the ASOS Ice-Free Wind Sensor Replacement 


Radar Vectors for the Stable Approach


The Importance of Pilot Weather Reports (PIREP)

/*RTEF/ Weather plays a dynamic role in our lives. This is more evident to us with a small accumulation of snow or a deluge of rain during a thunderstorm. The rapid change in weather conditions poses threats to pilots during critical stages of navigation. Whether the conditions are en route or at the destination airports, weather impacts must be reported as conditions change. All controllers should be proactive in their requests for PIREPs consistent with priority of duties.

It is very important to get up-to-the-minute updates of weather conditions and forward this information to pilots, other controllers, and the National Weather Service or reporting agency for dissemination. Handling of PIREPs is detailed in FAAO 7210.3, Section 3, paragraph 6-3-1, for en route and Part 3, Chapter 10, paragraph 10-3-1, for terminal facilities.

We cannot emphasize enough the benefits of getting PIREP information. PIREPs on cloud layers, turbulence, icing, convective activity, low-level wind shear are of paramount importance. Most of these phenomena can only be observed by the pilot. Controllers use this information to reroute traffic and in pilot weather briefings for increased safety. Forecasters use PIREP information in airmen's meteorological information (AIRMETs), significant meteorological information (SIGMETs) and center weather advisories.

Controllers shall advise pilots of hazardous weather that may impact operations within 150 NM of their sector or area of jurisdiction. Solicit PIREPs when requested or when one of the following conditions exists or is forecast for your area of jurisdiction: ceilings at or below 5,000 feet to include cloud base/top reports when feasible, visibility (surface or aloft) at or less than 5 miles, thunderstorms and related phenomena, turbulence of moderate degree or greater, icing of light degree or greater, wind shear, volcanic ash clouds, and when braking action advisories are in effect (FAAO 7110.65, Air Traffic Control, paragraph 2-6-3, PIREP Information). The situations  listed above require PIREPs, but PIREPs can be requested at any time. PIREPs shall include time, aircraft position, type aircraft, altitude. When the PIREP involves icing, include the icing type, intensity, and the air temperature in which icing is occurring.

It is very important to request flight conditions from the pilot, as it is our only notification of impending or potential danger to flight operations. In areas of significant weather, planning ahead can help resolve problems before they exist. Controllers can suggest alternative routes or altitudes to pilots if the weather situation affects that facility. Forwarding PIREP information helps the air traffic system and affected users. Disseminated PIREP data can be in the form of an advisory such as a hazardous inflight weather advisory (HIWAS), AIRMET, SIGMET, center weather advisories, or urgent pilot weather reports.

The internal coordination procedures for notifying affected facilities shall be specified in a facility directive. Specifics are contained in FAAO 7210.3, Facility Operation and Administration, paragraph 6-3-1 for en route facilities and paragraph 10-3-1 for terminal facilities.

FAAO 7110.10, Flight Services, has standardized the PIREP format with other reports and forecasts. Since PIREPs are available to forecasters, controllers, dispatchers, and pilots alike, correct format is essential. One specific area of concern is the location of the weather event. Various automated programs alert forecasters and automatically plot data concerning weather phenomena. This information is used to assist forecasters and is archived for research. Incorrectly formatted PIREPs are often lost. This has the potential to seriously affect aviation safety.

The requirement to issue weather and solicit PIREPs cannot be overemphasized. The benefits to multiple users can greatly reduce problems for pilots as they strive to navigate away from hazardous weather. Specific references for PIREPs can be found in FAAO 7110.65, Air Traffic Control, Chapter 2, Section 6, Weather Information, and FAAO 7110.10, Flight Services, Chapter 9, Section 2, Pilot Weather Report (UA/UUA). (ATP-120)

Radio Communications

/*TRE/ In December 2001, we started publishing Air Traffic Bulletin articles on a biannual basis to remind controllers to use standard phraseology and to speak at a reasonable rate when communicating with pilots, especially those whose primary language is not English.

The National Transportation Safety Board noted several runway incursion incidents in 1999 involved flight crews whose primary language was not English.

In controller-to-pilot communications, understanding is critical. We encourage controllers to speak at a reasonable rate and use standard words and phrases to promote understanding and lessen the possibilities for confusion between controllers and pilots. (ATP-120)

Prevailing Visibility

/*RTE/ Prevailing visibility observations are important. What is prevailing visibility? Prevailing visibility is the greatest horizontal visibility equaled or exceeded throughout at least half the horizon circle which need not necessarily be continuous. Prevailing visibility reports are required at the usual point of observation, and at the tower level, when the visibility is less than 4 miles.

Once the visibility is less than 4 miles, tower personnel shall take prevailing visibility observations. When the tower is responsible for visibility reports, keep in mind to use the lower of the two observations (tower or surface) for aircraft operations. This provides a safety net for operations to ensure that legal requirements of the regulations are met. If the weather sequence shows the visibility of 2 miles, but the tower's prevailing visibility is 3 miles, the airport remains IFR until the weather sequence is altered to reflect the prevailing visibility data. This impacts tall towers that can be above the weather conditions.

Also, forward tower visibility observations to the weather observer. This is required to ensure the weather observer is aware that visibility differences exist and to change the weather sequence. This encourages the weather change to be broadcast systemwide.

The tower must notify the weather observer of subsequent changes so the weather observer can update the official weather. This is especially important when the official weather changes to a condition in which the layer is below 1,000-foot ceiling or below the highest circling minimum, whichever is greater, or if the visibility is less than 3 miles. When the prevailing visibility improves beyond 4 miles, the weather observer is responsible for visibility reports.

Notify the appropriate control facility of changes to visibility. This increases the safety by advising neighboring facilities who can advise pilots of changes to visibility values. It is important to forward current weather changes to the appropriate control facility. More detailed information is available in FAAO 7110.65, Air Traffic Control, paragraph 4-7-10.      (ATP-120)

Delay Reporting

/*TRE/ FAAO 7210.3, Facility Operation and Administration, paragraphs 17-5-3 and 17-5-4, provides direction as to the communication that must be affected when reportable delays are incurred, or are expected to be incurred. A reportable delay is one that reaches 15 minutes.

Terminal facilities must coordinate with the appropriate air route traffic control center traffic management unit (ARTCC TMU) to ensure they are kept aware of situations and conditions which may require the implementation of traffic management (TM) initiatives. Likewise, the ARTCC TMU must keep the Air Traffic Control System Command Center (ATCSCC) apprised of situations and conditions which may necessitate TM initiatives. Part of this process is the requirement to notify either the ARTCC TMU or the ATCSCC, whichever is appropriate, of any arrival, departure, or en route delay reaching or expected to reach 15 minutes. The facility must continue to report any change in delay time in 15-minute increments, until such time as delays are reported to be less than 15 minutes. The only exception is when the delay is an expected departure clearance time (EDCT) created by a ground delay program. (This exception will be reflected in future publications of the order.)

The notification should be made in a timely manner, and shall include the projected delay and the number of aircraft expected to encounter delay. The ATCSCC shares the information regarding the potential for delays with the user community which facilitates enhanced planning and communication. It also allows the ATCSCC to pursue avenues of relief from a system perspective. If notification is not made until after the delays have been incurred, the opportunity to evaluate the impacting conditions and possibly reduce or negate the delays has been eliminated.

In addition to the above requirements, FAAO 7210.3, paragraph 17-5-6, sets forth the requirement for each facility to notify the ATCSCC when delays exceed 90 minutes. This is true in all cases except when the delay is an EDCT created by a ground delay program. One of the primary reasons for this requirement is to preclude a flight from incurring an unnecessary, excessive delay in the event the associated TM initiative causing the delay has been cancelled.

With proper and timely notification of delays, the facilities can work together to strive for a more efficient, productive air traffic system. (ATT-210)

Discretionary Descent

/*RTE/ It is no secret that airlines and other air traffic service recipients would like to reduce costs. One controller/air traffic control (ATC) tool available to assist in this endeavor is discretionary descent. Pilots of all aircraft benefit from being authorized a discretionary descent. This procedure allows the pilot to temporarily remain at the last assigned altitude to take advantage of favorable winds or reduced fuel consumption. Conversely, a pilot authorized to descend via pilot's discretion may choose to descend rapidly to escape unfavorable winds or weather. Aircraft with flight management systems can take advantage of uninterrupted descents, and these uninterrupted descents can reduce noise and increase safety since fewer aircraft configuration changes reduce pilot workload. A pilot less distracted by workload should be better able to listen for new or revised ATC instructions thereby reducing controller workload. Whenever traffic permits, it is recommended that a controller utilize this procedure.

There are several ways to assign a discretionary descent. A cruise clearance allows a great deal of pilot discretion. This clearance assigns a block of airspace to a pilot from the minimum IFR altitude up to and including the altitude specified in the cruise clearance. While this clearance would rarely be used for an aircraft at high altitude, an instruction to climb/descend at pilot's discretion or a crossing restriction when used in conjunction with altitude assignments means that ATC has offered the pilot the option to start the climb or descent whenever he/she wishes and conduct the climb or descent at any rate he/she wishes. (ATP-120)

Minimum Safe Altitude Warning (MSAW) Safety Alert Clarification

/*RT/ A recent change to FAAO 7110.65, Air Traffic Control, paragraph 2-1-6, Safety Alerts, was effective February 20, 2003. An additional line has been added.

If a TRACON has given control of an aircraft to one of its remote towers, and the tower has aural and visual MSAW alert capability, the TRACON does not have to inform the tower controller if an alert is observed for that aircraft. The important part to stress with this change is both qualifiers of this discontinuance must apply. The remote tower must have an aural alarm capability and visual alert capability.

This applies to a tower with a certified radar, with an aural alarm in the cab. Prior to discontinuing MSAW notification with the tower in question, the tower configuration and MSAW alerting equipment should be known to the TRACON. The intention of this paragraph is not to reduce the effectiveness of MSAW alerting procedures, but to eliminate a requirement for nuisance notification. (ATP-120)

Frequently Asked Questions about Expect Departure Clearance Times (EDCT) associated with a Ground Delay Program (GDP)


What is the change?

Notice 7110.318: This GENOT retains the current EDCT window, 5 minutes before until 5 minutes after the EDCT. It also provides guidance for releasing flights on their assigned EDCT when the flights are early, on time, or late. This change will be reflected in FAAO 7110.65 in February 2004.

What is the EDCT window?
The window for meeting an EDCT is 5 minutes before until 5 minutes after the EDCT. The aircraft operator is responsible to operate in a manner consistent with departing within the EDCT window. ATC should provide the departing flight every opportunity to meet the EDCT.

What if a flight taxis consistent with meeting the EDCT window?

An aircraft may taxi consistent with meeting the EDCT, but may be delayed by something outside the pilot's control, such as an aircraft emergency or airport surface constraint. The flight should be released even if it is outside the EDCT window. The facility is not required to coordinate the late departure. When time permits, document the event for next-day quality assurance.

What if a flight taxis late or requests taxi too late to meet the EDCT window?

Call the ATCSCC through the appropriate TMU for a new EDCT.

What if an aircraft taxis too early to meet the EDCT window?

There are many reasons why a flight may taxi too early for an EDCT. The pilot may have an earlier EDCT than the tower indicates. There may have been several changes to an aircraft's EDCT due to substitutions and revisions to the GDP. Due to communications network delays, the most current time may not be available in the tower. In some cases, the aircraft may need to leave the gate so that another aircraft may use it. The controller should first verify the EDCT with the pilot. If the pilot's EDCT agrees with the tower's EDCT, then the flight should be held on the airport and released within the EDCT window. If the pilot's EDCT does not agree with the tower's EDCT, then apply the Trust and Verify procedures.

What is Trust and Verify?

Trust and Verify was adopted to ensure that an aircraft would not be held past its EDCT when there was a discrepancy between the pilot's EDCT and the tower's EDCT. There are many reasons why the tower might not have an updated EDCT, and subjecting the flight to additional delay may not be appropriate. If the pilot's EDCT is different, and there is time to verify the EDCT via the Flight Schedule Monitor (where available) or through coordination with the ATCSCC through the appropriate TMU, then do so. Verification must be completed prior to the pilot-provided EDCT. If the verification cannot be completed, release the aircraft and report the discrepancy to the ATCSCC through the appropriate TMU. If the verification is completed, the aircraft should be released consistent with the verified EDCT, unless otherwise coordinated. If there is time, documenting the event may be useful for next-day analysis.

What is the impact of departing before or after the EDCT window?

The EDCT is calculated based on the arrival slot at the destination. When flights do not depart within the EDCT window, it can create disorder at the arrival end of the flight. Extra flights where they are not expected can create an excessive holding situation. Too much holding at the arrival airport often results in diversions and added workload, including the possibility of a ground stop, a revision to the GDP and new EDCTs being issued for most of the aircraft. A national GDP requires facility personnel and system users to prioritize operations to insure GDP aircraft can meet the EDCT window.


Effectively meeting EDCTs requires ATC and system users to work together to meet the EDCT window. Aircraft operators must load their passengers and cargo and be ready to taxi in a manner consistent to meet the EDCT window. ATC must issue control instructions consistent with meeting the window. This is based on the specific airport environment. For example, a busy hub airport at 5:00 p.m. on a weekday afternoon is going to be different from that same airport during a lull in the middle of the morning. Neither air traffic nor the aircraft operator can be successful without the cooperation of the other. In order to improve system efficiency, it is incumbent upon all affected parties to participate fully in ensuring EDCT compliance to the maximum extent possible. (ATT‑1)

Use of the Automated Surface Observing System (ASOS) Ice-Free Wind Sensor Replacement

/*TF/ Air Traffic has agreed to provide employees with a briefing describing the ASOS ice-free wind sensor including the expected benefits of this change.

The ASOS product improvement program will implement a replacement wind sensor that will perform better in adverse winter conditions such as freezing rain, freezing drizzle, and snow. The current ASOS wind sensor (Belfort 2000) uses rotating cups to measure wind speed and a vane to measure wind direction and is adversely affected by adverse winter conditions.

The new ASOS wind sensor will now use the 3-second World Meteorological Organization (WMO) gust standard for processing gust and peak winds. The new ASOS wind sensor (Vaisala 425NWS) is a sonic anemometer. It has no moving parts to freeze in winter weather conditions. The 2-minute wind speed averaging remains the same, however, the highest 3-second running average speed will be stored for gust and peak wind processing versus storing the highest 5-second discrete average wind speed for gust and peak wind processing.

While there will be negligible changes in the 2-minute average wind speed and direction reporting, the changes in gust and peak wind reporting will be seen as higher gust speeds and slightly more frequent gust reporting. The new sensor will be more responsive to quick changes with no moving parts and some previously masked and smoothed gust will now be reportable. There is no change in how the air traffic control specialists will provide the surface wind information data to the aviation community.

Full-scale deployment of the new sensor has begun and will extend through September 2006, with the bulk of the National Weather Service sites receiving new sensors in 2004 and the bulk of FAA sites receiving the new sensor in 2006. (ATB-460)



Radar Vectors for the Stable Approach    

A few years ago, a Southwest B-737 attempted a landing at an airport and ended up rolling at high-speed off of the runway, through the airport perimeter fence, and across a road, before stopping at a gasoline station. Did the pilots say, "Fill 'er up!" upon arrival? All joking aside, the crew and passengers were very lucky as there were no deaths or serious injuries. The aircrew's decision to continue an unstable approach to landing was named as the direct cause, and air traffic control was named as a contributor to the accident.

Many unstable approaches have resulted in accidents or incidents. In some of the cases, air traffic has set the stage by putting the aircraft in a position for the unstable approach and then the aircrew has elected to continue the approach anyway. Not all unstable approaches end up as hair-raising incidents or accidents. However, all unstable approaches reveal that a mistake in judgment has occurred in the cockpit. However, the controller's poor judgment or lack of care can place the aircraft in a position for the pilot to make the final series of mistakes to the runway. This edition of Incident'ly will discuss the unstable approach and give you some insight into what may be happening in the cockpit and what the pilot is up against when presented with the setup for an unstable approach. We'll show you how the controller can be the catalyst for starting the problem and how to help prevent the occurrence of such an event.

The Stable Approach

An ILS approach is set up with a glidepath that will allow an aircraft to descend at a rate of 300 feet per nautical mile traveled forward. (Yes, Virginia, there are some approaches with slightly different descent rates, but the 3 degree or 300 feet per mile rate is the most common.) An excellent description of the stabilized approach concept can be found in the FAAO 8400.10, Air Transportation Operations Inspector's Handbook, paragraph 511, Stabilized Approach Concept, which is quoted at the end of this article for those who are interested in the details.

The Unstable Approach

Most major air carriers require their flight crews to have the aircraft stabilized earlier than the requirements referred to in the Air Transportation Operations Inspector's Handbook. For example, one major airline describes an unstabilized approach as one where:

         Gear or flaps are not in the landing configuration by the final approach fix (FAF) in instrument meteorological conditions (IMC) or 1,000 feet in visual meteorological conditions (VMC).

         A sustained sink rate in excess of 1,000 feet per minute inside the FAF (IMC) or below 1,000 feet (VMC) in order to regain the normal descent profile.

         Excessive airspeed with minimal deceleration inside of the FAF (IMC) or below 1,000 feet (VMC).

         Slightly high and slightly fast inside of the FAF (IMC) or below 1,000 feet (VMC).

         Auto thrust mismanagement inside of the FAF (IMC) or below (VMC) causing excessive thrust and thus causing excessive speed.

An unstable approach is an approach where the aircraft is too fast or too high, not spooled up, or all three. This condition can be caused by piloting error or by poor controller vectoring technique. In the latter case, the pilot is forced to correct for the controller's mistakes, and in some cases, it is not possible. If the pilot concedes the blunder, a go-around is in order. Sometimes, the pilot will attempt to correct the error and in turn make a greater judgment error that can end up as a hair-raising arrival sequence or an accident.

The unstable approach works like this. The visual or electronic glidepath is designed so that the aircraft will descend at a constant rate. Visual glidepath information is provided by a visual approach slope indicator (VASI), precision approach path indicator (PAPI), etc., and electronic glidepath information is provided to the pilot by the flight director or combination of cockpit instruments (artificial horizon, localizer/glideslope indicator, etc.). The pilot will aim for the touchdown zone or touchdown aim point, which is located 1,000 feet from the runway threshold. If the aircraft is too fast and/or too high (above the glidepath), the aircraft will touch down beyond the touchdown zone. When this happens, there may not be enough runway length remaining for the pilot to stop the aircraft on the runway.

When the aircraft is too high, the pilot will have to correct the situation and rapidly descend or dive the aircraft to get on the glidepath. This will increase the airspeed and make the aircraft more difficult to slow for the landing. If the speed is not bled off by the decision point and the pilot decides to land anyway, the aircraft will still want to fly because the excess speed translates into lift. The aircraft will float down the runway until enough speed is finally bled off for the wing to stop flying and allow touchdown, often with not enough runway left to stop in. But, if the pilot instead continues the rapid descent and plants the aircraft firmly on the runway, its excessive speed can take it down the runway and across country before the brakes and thrust reversers (if the aircraft has reversers) can stop it. (Of course, if the planting of the aircraft was firm enough, airspeed will have been bled off and forward progress will be appreciably less. In fact, the broken airplane may stay in the smoking hole it made or the pieces made by the sudden deceleration may slide down the runway a bit due to inertia.)

The pilot, who finds the aircraft high and fast, could slow the aircraft down to its appropriate approach speed instead of increasing the speed by the dive, but in so doing, the aircraft will not have descended and will be above the glidepath. This means that it will touch down too far down the runway and be no better off than the high-speed touchdown. In both cases the aircraft will probably end up going off the runway and cross‑country. Conversely, if the pilot allows the aircraft to get below the glidepath and remain there, the aircraft will land short of the runway. Spending any time below glidepath is risky, and in the severest cases, the aircraft will strike obstructions or the ground, as did an American Airlines MD88 that clipped trees on the approach and crashed on the runway at Bradley International Airport, Connecticut.

The aircraft needs to have its speed and descent rate stable and the engines spooled (powered) up during the descent on the glideslope. The reason for this is so that the pilot can correct for downdrafts and, if necessary, be able to stop the descent and develop a constant rate of climb during a go-around or missed approach. If the aircraft is too high and too fast, the pilot will have to reduce the power setting to slow and descend the aircraft, which can put him/her in the position of not having enough thrust available to execute a successful go-around or missed approach. Instead, the aircraft will continue to sink and by the time the engines are spooled up and developing enough power to climb or stop the sink rate, the aircraft will have hit the ground.

In addition to the above problems during the unstable approach, the pilot workload increases dramatically. The pilot's attention will be more inside the cockpit while he/she is trying to slow and descend the aircraft and get it on glidepath. This is a big distraction because many more concerns are added to the problem of managing the aircraft that the pilot must now think about. Add in the downdrafts and updrafts that can accompany approaches as well as turbulence and wind-shears that will cause excursions from the glidepath, and workload can become deadly. If the flight is being conducted in VFR conditions, the crew's workload will increase so that their ability to see and avoid traffic activities will be much reduced, if not eliminated entirely.

Inside the Final Approach Fix on the ILS

The final approach fix is generally situated anywhere from 3 to 5 miles from the runway threshold. The pilot will normally prepare the aircraft so that it is configured and ready to fly a stabilized descent by the time the aircraft intercepts the glideslope. If the controller has not allowed the pilot time to do this, then the pilot has to scramble to get the aircraft stabilized in 5 miles or less and before it descends below the stabilized approach heights. At 180 knots, the aircraft will travel approximately 3 miles in 1 minute. Air carrier jets will fly the glideslope at approximately 140 to 130 knots indicated airspeed. Even at the130-knot rate, 5 miles will be traveled in about 2 minutes and 10 seconds. If the aircraft is high or fast or both, you can see that the crew will be very rushed and tasked to the maximum to accomplish stabilizing the aircraft and preparing it for landing in such a short time frame. Truly, the crew should refuse the approach and execute a missed approach. However, they may attempt to continue with what they know is a bad deal. That is what happened to the Southwest crew. The controller kept him high and fast and turned him close in onto the approach path. The pilot should have taken action to mitigate the situation or not have agreed to the plan and executed a missed approach. However pilots have a keen desire to stay on schedule and complete the mission and they sometimes overestimate their ability to repair a bad situation that is handed to them. Time is money, and a go-around just seems unappealing. It's no excuse for bad pilot judgment, but again, there is no excuse for the controller's equally poor judgment and/or bad service either.

The Efficiency of Radar Vectors

Without the controller to provide radar vectors to the final or feeder routes/distance measuring equipment (DME) arcs, a pilot will fly some sort of procedure turn before crossing the final approach fix inbound. The procedure turn allows the pilot to prepare the aircraft for the final descent at the FAF. All of the elements that a controller is tasked with are contained in a published instrument procedure turn. (Thirty-degree course intercept, time to establish the aircraft on the final approach course before glideslope intercept at the FAF as well as time to configure the aircraft for a stabilized approach.) Controller radar vectors are a replacement for the procedure turn and should be more efficient in that the course reversal necessary in all but the feeder route approach to the final approach course is eliminated. But, if the controller vectors the aircraft in such a way that it is placed high or fast, and/or too close to the FAF, the benefits of the vectors can be lost when a go-around or missed approach has to be executed as a result.

How You Can Help

Vector arrival aircraft so that the pilot has time to prepare the aircraft for arrival. It takes some time to transition from the airspeed the controller assigned the pilot to the preferred airspeed that will get the desired groundspeed and rate of descent to stay on glideslope.

When possible, get the aircraft down to the correct altitude well before the turn to final. If the aircraft must be turned onto the final approach course while descending, think about what descent rate and distance to the FAF the aircraft will have to deal with. If your aircraft is still high and fast, it will need distance to get squared away. The aircraft may need to be turned onto final 10 miles outside the FAF instead of 3 or 5 miles. Don't set the aircraft up for a Disneyland type "E" ticket ride to the runway!

Descent rates on the glideslope will vary depending upon the aircraft's groundspeed. For example, at a groundspeed of 120 knots, the aircraft will descend at a rate of 600 feet per minute to stay on a 3 degree glidepath. At a 180-knot groundspeed, the rate will increase to approximately 900 feet per minute. At a 240‑knot groundspeed, the rate will be approximately 1,200 feet per minute, but such a high rate of descent will cause the ground proximity warning to activate, which requires a missed approach. So, if you have placed the aircraft 2 miles from the FAF on the final approach course so high that the pilot needs a 3,000 or greater feet per minute rate of descent to get to an altitude where the glideslope can be captured, you will have set the pilot up for a possible unstable approach. The high rate of descent approaches can be exciting and things happen very fast. That 240‑knot groundspeed will cover the 5 miles from FAF to MAP in about 1 minute and change, and the transition from the 1,200 feet per minute rate of descent to a rate that will provide a touchdown will be all but impossible! If a missed approach is not conducted, a "smashdown" will probably result.

The point to be made is that if the controller vectors for high/fast/close approaches, the pilot has to worry about three-dimensional problems. The pilot will have to descend the aircraft at a too-high rate in a too-short distance and slow to an approach speed that will get it on glidepath in a too-short time period and not wreck the aircraft doing it.

         Don't insist that the pilot fly greater than 180 knots to the final approach fix.

         Assure that the aircraft is given headings that provide a ground track of 30 degrees or less to intercept the final approach course.

         Assure that the aircraft will be established on the final approach course 2 miles outside of the approach gate and no closer than the final approach fix when appropriate.

         Don't "slam dunk" the aircraft at the marker.

         Be professional and precise. It takes no skill to "slam dunk" an aircraft to final, nor to issue high and fast approaches.

It truly takes skill and timing to do it right. It is hard to learn to calculate the compression on final that must occur in order for aircraft to land safely. These skills are what make a good controller. If your skills are rusty in these areas, ask for skill enhancement sessions to hone your skills and keep your skills at professional levels.

         Don't be part of the problem.

         Don't put a pilot in the position where he/she has to correct for your mistakes.

         Don't put a pilot in a position where he/she can do a foolish thing.

         Don't contribute to accidents or incidents. Help prevent them.

The following is from FAAO 8400.10, Air Transportation Operations Inspector's Handbook, paragraph 511, Stabilized Approach Concept. "In instrument weather conditions, a pilot must continuously assess instrument information throughout an approach to properly maneuver the aircraft (or monitor autopilot performance) and to decide on the proper course of action at the decision point (decision height (DH) or minimum descent altitude (MDA)/missed approach point (MAP)). Significant speed and configuration changes during an approach can seriously complicate tasks associated with aircraft control, increase the difficulty of properly evaluating an approach as it progresses, and complicate the decision of the proper action to take at the decision point. The handling and engine response characteristics of most turbojet aircraft further complicate pilot tasks during approach and landing operations. A pilot must begin formulating a decision concerning the probable success of an approach before reaching the decision point. The pilot's decision making process requires the pilot to be able to determine displacements from the course or glidepath centerline, to mentally project the aircraft's three-dimensional flightpath by referring to flight instruments, and to then apply control inputs as necessary to achieve and maintain the desired approach path. This process is simplified by maintaining a stable approach speed, descent rate, vertical flightpath, and configuration during the final stages of an approach. Maintaining a stable speed, descent rate, vertical flightpath, and configuration is a procedure commonly referred to as the stabilized approach concept.

Operational experience has shown that the stabilized approach concept is essential for safe operations with turbojet aircraft, and it is strongly recommended for all other aircraft. Configuration changes at low altitude should be limited to those changes which can be easily accommodated without adversely affecting pilot workload. A stabilized approach for turbojet aircraft means that the aircraft must be in an approved landing configuration (including circling configuration, if appropriate), must maintain the proper approach speed with the engines spooled up, and must be established on the proper flightpath before descending below the minimum "stabilized approach height" specified for the type of operation being conducted. These conditions must be maintained throughout the rest of the approach for it to be considered a stabilized approach. Operators of turbojet aircraft must establish and use procedures which result in stabilized approaches. Pilots operating propeller driven aircraft should also maintain a stable speed and flightpath on final approach. A stabilized approach must be established before descending below the following minimum stabilized approach heights:

         500 feet above the airport elevation during VFR or visual approaches and during straight-in instrument approaches in VFR weather conditions.

         MDA or 500 feet above airport elevation, whichever is lower, if a circling maneuver is to be conducted after completing an instrument approach.

         1,000 feet above the airport or touchdown zone elevation during any straight-in instrument approach in instrument flight conditions.

         1,000 feet above the airport during contact approaches."  (AAT-20)


Questions/comments about content should be addressed to ATP-100