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AIM

10/12/17

6

−4−1

Two-way Radio Communications Failure

Section 4. Two-way Radio Communications Failure

6

−4−1. Two-way Radio Communications

Failure

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 circum-
stances, 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 communica-
tions 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 encoun-
tered after the failure, each pilot must continue the
flight under VFR and land as soon as practicable.

NOTE

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:

(a) Route.

(1)

By the route assigned in the last ATC

clearance received;

(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.

NOTE

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

operations.

Upon reaching the time/fix specified, the pilot should
commence climbing to the altitude advised to expect. If the