Aeronautical Information Manual (AIM), page 441

Index   440 -- Page 441 -- 442

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 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.

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

(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

Two-way Radio Communications Failure 6-4-1

Page 441 of the Aeronautical Information Manual (AIM.pdf)
AIM: Official Guide to Basic Flight Information and ATC Procedures

Index   440 -- Page 441 -- 442