294 

14 CFR Ch. I (1–1–19 Edition) 

Pt. 121, App. G 

3. 

Equipment and equipment installation—In-

ertial Navigation Systems 

(

INS

). (a) If an appli-

cant elects to use an Inertial Navigation 
System it must be at least a dual system (in-
cluding navigational computers and ref-
erence units). At least two systems must be 
operational at takeoff. The dual system may 
consist of either two INS units, or one INS 
unit and one Doppler Radar unit. 

(b) Each Inertial Navigation System must 

incorporate the following: 

(1) Valid ground alignment capability at 

all latitudes appropriate for intended use of 
the installation. 

(2) A display of alignment status or a ready 

to navigate light showing completed align-
ment to the flight crew. 

(3) The present position of the airplane in 

suitable coordinates. 

(4) Information relative to destinations or 

waypoint positions: 

(i) The information needed to gain and 

maintain a desired track and to determine 
deviations from the desired track. 

(ii) The information needed to determine 

distance and time to go to the next waypoint 
or destination. 

(c) For INS installations that do not have 

memory or other inflight alignment means, 
a separate electrical power source (inde-
pendent of the main propulsion system) must 
be provided which can supply, for at least 5 
minutes, enough power (as shown by analysis 
or as demonstrated in the airplane) to main-
tain the INS in such condition that its full 
capability is restored upon the reactivation 
of the normal electrical supply. 

(d) The equipment must provide such vis-

ual, mechanical, or electrical output signals 
as may be required to permit the flight crew 
to detect probable failures or malfunctions 
in the system. 

4. 

Equipment and equipment installation— 

Doppler Radar Systems. 

(a) If an applicant 

elects to use a Doppler Radar System it 
must be at least a dual system (including 
dual antennas or a combined antenna de-
signed for multiple operation), except that: 

(1) A single operating transmitter with a 

standby capable of operation may be used in 
lieu of two operating transmitters. 

(2) Single heading source information to 

all installations may be utilized, provided a 
compass comparator system is installed and 
operational procedures call for frequent 
cross-checks of all compass heading indica-
tors by crewmembers. 

The dual system may consist of either two 
Doppler Radar units or one Doppler Radar 
unit and one INS unit. 

(b) At least two systems must be oper-

ational at takeoff. 

(c) As determined by the Administrator 

and specified in the certificate holder’s oper-
ations specifications, other navigational aids 
may be required to update the Doppler Radar 
for a particular operation. These may in-

clude DME, VOR, ADF, ground-based radar, 
and airborne weather radar. When these aids 
are required, the cockpit arrangement must 
be such that all controls are accessible to 
each pilot seated at his duty station. 

5. 

Training programs. 

The initial training 

program for Doppler Radar and Inertial 
Navigation Systems must include the fol-
lowing: 

(a) Duties and responsibilities of flight 

crewmembers, dispatchers, and maintenance 
personnel. 

(b) For pilots, instruction in the following: 
(1) Theory and procedures, limitations, de-

tection of malfunctions, preflight and 
inflight testing, and cross-checking methods. 

(2) The use of computers, an explanation of 

all systems, compass limitations at high 
latitudes, a review of navigation, flight plan-
ning, and applicable meteorology. 

(3) The methods for updating by means of 

reliable fixes. 

(4) The actual plotting of fixes. 
(c) Abnormal and emergency procedures. 
6. 

Equipment accuracy and reliability. 

(a) 

Each Inertial Navigation System must meet 
the following accuracy requirements, as ap-
propriate: 

(1) For flights up to 10 hours’ duration, no 

greater than 2 nautical miles per hour of cir-
cular error on 95 percent of system flights 
completed is permitted. 

(2) For flights over 10 hours’ duration, a 

tolerance of 

±

20 miles cross-track and 

±

25 

miles along-track on 95 percent of system 
flights completed is permitted. 

(b) Compass heading information to the 

Doppler Radar must be maintained to an ac-
curacy of 

±

1

° 

and total system deviations 

must not exceed 2

°

. When free gyro tech-

niques are used, procedures shall be utilized 
to ensure that an equivalent level of heading 
accuracy and total system deviation is at-
tained. 

(c) Each Doppler Radar System must meet 

accuracy requirements of 

±

20 miles cross- 

track and 

±

25 miles along-track for 95 per-

cent of the system flights completed. Updat-
ing is permitted. 

A system that does not meet the require-
ments of this section will be considered a 
failed system. 

7. 

Evaluation program. 

(a) Approval by eval-

uation must be requested as a part of the ap-
plication for operational approval of a Dopp-
ler Radar or Inertial Navigation System. 

(b) The applicant must provide sufficient 

flights which show to the satisfaction of the 
Administrator the applicant’s ability to use 
cockpit navigation in his operation. 

(c) The Administrator bases his evaluation 

on the following: 

(1) Adequacy of operational procedures. 
(2) Operational accuracy and reliability of 

equipment and feasibility of the system with 
regard to proposed operations. 

VerDate Sep<11>2014 

08:20 May 17, 2019

Jkt 247048

PO 00000

Frm 00304

Fmt 8010

Sfmt 8002

Y:\SGML\247048.XXX

247048