Section 4. Two‐way Radio Communications Failure
6-4-1. Two‐way Radio Communications
a. It is virtually impossible to provide regulations
and procedures applicable to all possible situations
associated with two‐way radio communications
failure. During two‐way radio communications
failure, when confronted by a situation not covered in
the regulation, pilots are expected to exercise good
judgment in whatever action they elect to take.
Should the situation so dictate they should not be
reluctant to use the emergency action contained in
14 CFR Section 91.3(b).
b. Whether two‐way communications failure
constitutes an emergency depends on the circumstances, and in any event, it is a determination made
by the pilot. 14 CFR Section 91.3(b) authorizes a
pilot to deviate from any rule in Subparts A and B to
the extent required to meet an emergency.
c. In the event of two‐way radio communications
failure, ATC service will be provided on the basis that
the pilot is operating in accordance with 14 CFR
Section 91.185. A pilot experiencing two‐way
communications failure should (unless emergency
authority is exercised) comply with 14 CFR
Section 91.185 quoted below:
1. General. Unless otherwise authorized by
ATC, each pilot who has two‐way radio communications failure when operating under IFR must comply
with the rules of this section.
2. VFR conditions. If the failure occurs in
VFR conditions, or if VFR conditions are encountered after the failure, each pilot must continue the
flight under VFR and land as soon as practicable.
This procedure also applies when two‐way radio failure
occurs while operating in Class A airspace. The primary
objective of this provision in 14 CFR Section 91.185 is to
preclude extended IFR operation by these aircraft within
the ATC system. Pilots should recognize that operation
under these conditions may unnecessarily as well as
adversely affect other users of the airspace, since ATC may
be required to reroute or delay other users in order to
protect the failure aircraft. However, it is not intended that
the requirement to “land as soon as practicable” be
construed to mean “as soon as possible.” Pilots retain the
prerogative of exercising their best judgment and are not
required to land at an unauthorized airport, at an airport
unsuitable for the type of aircraft flown, or to land only
minutes short of their intended destination.
3. IFR conditions. If the failure occurs in IFR
conditions, or if subparagraph 2 above cannot be
complied with, each pilot must continue the flight
according to the following:
(1) By the route assigned in the last ATC
(2) If being radar vectored, by the direct
route from the point of radio failure to the fix, route,
or airway specified in the vector clearance;
(3) In the absence of an assigned route, by
the route that ATC has advised may be expected in a
further clearance; or
(4) In the absence of an assigned route or a
route that ATC has advised may be expected in a
further clearance by the route filed in the flight plan.
(b) Altitude. At the HIGHEST of the
following altitudes or flight levels FOR THE ROUTE
SEGMENT BEING FLOWN:
(1) The altitude or flight level assigned in
the last ATC clearance received;
(2) The minimum altitude (converted, if
appropriate, to minimum flight level as prescribed in
14 CFR Section 91.121(c)) for IFR operations; or
(3) The altitude or flight level ATC has
advised may be expected in a further clearance.
The intent of the rule is that a pilot who has experienced
two-way radio failure should select the appropriate
altitude for the particular route segment being flown and
make the necessary altitude adjustments for subsequent
route segments. If the pilot received an “expect further
clearance” containing a higher altitude to expect at a
specified time or fix, maintain the highest of the following
altitudes until that time/fix:
(1) the last assigned altitude; or
(2) the minimum altitude/flight level for IFR
Upon reaching the time/fix specified, the pilot should
commence climbing to the altitude advised to expect. If the
radio failure occurs after the time/fix specified, the altitude
to be expected is not applicable and the pilot should
maintain an altitude consistent with 1 or 2 above. If the
pilot receives an “expect further clearance” containing a
lower altitude, the pilot should maintain the highest of 1 or
2 above until that time/fix specified in subparagraph (c)
Leave clearance limit, below.
1. A pilot experiencing two‐way radio failure at an
assigned altitude of 7,000 feet is cleared along a direct
route which will require a climb to a minimum IFR altitude
of 9,000 feet, should climb to reach 9,000 feet at the time
or place where it becomes necessary (see 14 CFR
Section 91.177(b)). Later while proceeding along an
airway with an MEA of 5,000 feet, the pilot would descend
to 7,000 feet (the last assigned altitude), because that
altitude is higher than the MEA.
2. A pilot experiencing two‐way radio failure while being
progressively descended to lower altitudes to begin an
approach is assigned 2,700 feet until crossing the VOR and
then cleared for the approach. The MOCA along the airway
is 2,700 feet and MEA is 4,000 feet. The aircraft is within
22 NM of the VOR. The pilot should remain at 2,700 feet
until crossing the VOR because that altitude is the
minimum IFR altitude for the route segment being flown.
3. The MEA between a and b: 5,000 feet. The MEA
between b and c: 5,000 feet. The MEA between c and d:
11,000 feet. The MEA between d and e: 7,000 feet. A pilot
had been cleared via a, b, c, d, to e. While flying between
a and b the assigned altitude was 6,000 feet and the pilot
was told to expect a clearance to 8,000 feet at b. Prior to
receiving the higher altitude assignment, the pilot
experienced two‐way failure. The pilot would maintain
6,000 to b, then climb to 8,000 feet (the altitude advised to
expect). The pilot would maintain 8,000 feet, then climb to
11,000 at c, or prior to c if necessary to comply with an
MCA at c. (14 CFR Section 91.177(b).) Upon reaching d,
the pilot would descend to 8,000 feet (even though the MEA
was 7,000 feet), as 8,000 was the highest of the altitude
situations stated in the rule (14 CFR Section 91.185).
(c) Leave clearance limit.
(1) When the clearance limit is a fix from
which an approach begins, commence descent or
descent and approach as close as possible to the
expect further clearance time if one has been
received, or if one has not been received, as close as
possible to the Estimated Time of Arrival (ETA) as
calculated from the filed or amended (with ATC)
Estimated Time En Route (ETE).
(2) If the clearance limit is not a fix from
which an approach begins, leave the clearance limit
at the expect further clearance time if one has been
received, or if none has been received, upon arrival
over the clearance limit, and proceed to a fix from
which an approach begins and commence descent or
descent and approach as close as possible to the
estimated time of arrival as calculated from the filed
or amended (with ATC) estimated time en route.
6-4-2. Transponder Operation During
Two‐way Communications Failure
a. If an aircraft with a coded radar beacon
transponder experiences a loss of two‐way radio
capability, the pilot should adjust the transponder to
reply on Mode A/3, Code 7600.
b. The pilot should understand that the aircraft
may not be in an area of radar coverage.
6-4-3. Reestablishing Radio Contact
a. In addition to monitoring the NAVAID voice
feature, the pilot should attempt to reestablish
communications by attempting contact:
1. On the previously assigned frequency; or
2. With an FSS or *ARINC.
b. If communications are established with an FSS
or ARINC, the pilot should advise that radio
communications on the previously assigned frequency has been lost giving the aircraft's position, altitude,
last assigned frequency and then request further
clearance from the controlling facility. The preceding
does not preclude the use of 121.5 MHz. There is no
priority on which action should be attempted first. If
the capability exists, do all at the same time.
*Aeronautical Radio/Incorporated (ARINC) is a commercial communications corporation which designs,
constructs, operates, leases or otherwise engages in radio
activities serving the aviation community. ARINC has the
capability of relaying information to/from ATC facilities
throughout the country.