517 

Federal Aviation Administration, DOT 

Pt. 135, App. A 

Instruments: Installation 

12. 

Arrangement and visibility. 

Each instru-

ment must meet FAR 23.1321 and in addition: 

(a) Each flight, navigation, and powerplant 

instrument for use by any pilot must be 
plainly visible to the pilot from the pilot’s 
station with the minimum practicable devi-
ation from the pilot’s normal position and 
line of vision when the pilot is looking for-
ward along the flight path. 

(b) The flight instruments required by FAR 

23.1303 and by the applicable operating rules 
must be grouped on the instrument panel 
and centered as nearly as practicable about 
the vertical plane of each pilot’s forward vi-
sion. In addition— 

(1) The instrument that most effectively 

indicates the attitude must be in the panel 
in the top center position; 

(2) The instrument that most effectively 

indicates the airspeed must be on the panel 
directly to the left of the instrument in the 
top center position; 

(3) The instrument that most effectively 

indicates altitude must be adjacent to and 
directly to the right of the instrument in the 
top center position; and 

(4) The instrument that most effectively 

indicates direction of flight must be adjacent 
to and directly below the instrument in the 
top center position. 

13. 

Airspeed indicating system. 

Each airspeed 

indicating system must meet FAR 23.1323 
and in addition: 

(a) Airspeed indicating instruments must 

be of an approved type and must be cali-
brated to indicate true airspeed at sea level 
in the standard atmosphere with a minimum 
practicable instrument calibration error 
when the corresponding pitot and static 
pressures are supplied to the instruments. 

(b) The airspeed indicating system must be 

calibrated to determine the system error, 
i.e., the relation between IAS and CAS, in 
flight and during the accelerate-takeoff 
ground run. The ground run calibration must 
be obtained between 0.8 of the minimum 
value of 

V

1

and 1.2 times the maximum value 

of 

V

1

, considering the approved ranges of al-

titude and weight. The ground run calibra-
tion is determined assuming an engine fail-
ure at the minimum value of 

V

1

. 

(c) The airspeed error of the installation 

excluding the instrument calibration error, 
must not exceed 3 percent or 5 knots which-
ever is greater, throughout the speed range 
from 

V

MO

to 1.3

V

S

1

with flaps retracted and 

from 1.3

V

SO

to 

V

FE

with flaps in the landing 

position. 

(d) Information showing the relationship 

between IAS and CAS must be shown in the 
Airplane Flight manual. 

14. 

Static air vent system. 

The static air vent 

system must meet FAR 23.1325. The altim-
eter system calibration must be determined 
and shown in the Airplane Flight Manual. 

Operating Limitations and Information 

15. 

Maximum operating limit speed V

MO

/

M

MO.

 

Instead of establishing operating limitations 
based on 

V

NE

and 

V

NO,

the applicant must es-

tablish a maximum operating limit speed 

V

MO

/

M

MO

as follows: 

(a) The maximum operating limit speed 

must not exceed the design cruising speed 

V

C

 

and must be sufficiently below 

V

D

/

M

D

or 

V

DF

/ 

M

DF

to make it highly improbable that the 

latter speeds will be inadvertently exceeded 
in flight. 

(b) The speed 

V

MO

must not exceed 0.8

V

D

/ 

M

D

or 0.8

V

DF

/

M

DF

unless flight demonstra-

tions involving upsets as specified by the Ad-
ministrator indicates a lower speed margin 
will not result in speeds exceeding 

V

D

/

M

D

or 

V

DF.

Atmospheric variations, horizontal 

gusts, system and equipment errors, and air-
frame production variations are taken into 
account. 

16. 

Minimum flight crew. 

In addition to 

meeting FAR 23.1523, the applicant must es-
tablish the minimum number and type of 
qualified flight crew personnel sufficient for 
safe operation of the airplane considering— 

(a) Each kind of operation for which the 

applicant desires approval; 

(b) The workload on each crewmember con-

sidering the following: 

(1) Flight path control. 
(2) Collision avoidance. 
(3) Navigation. 
(4) Communications. 
(5) Operation and monitoring of all essen-

tial aircraft systems. 

(6) Command decisions; and 
(c) The accessibility and ease of operation 

of necessary controls by the appropriate 
crewmember during all normal and emer-
gency operations when at the crewmember 
flight station. 

17. 

Airspeed indicator. 

The airspeed indi-

cator must meet FAR 23.1545 except that, the 
airspeed notations and markings in terms of 

V

NO

and 

V

NH

must be replaced by the 

V

MO

/ 

M

MO

notations. The airspeed indicator mark-

ings must be easily read and understood by 
the pilot. A placard adjacent to the airspeed 
indicator is an acceptable means of showing 
compliance with FAR 23.1545(c). 

Airplane Flight Manual 

18. 

General. 

The Airplane Flight Manual 

must be prepared under FARs 23.1583 and 
23.1587, and in addition the operating limita-
tions and performance information in sec-
tions 19 and 20 must be included. 

19. 

Operating limitations. 

The Airplane 

Flight Manual must include the following 
limitations— 

(a) 

Airspeed limitations. 

(1) The maximum 

operating limit speed 

V

MO

/

M

MO

and a state-

ment that this speed limit may not be delib-
erately exceeded in any regime of flight 
(climb, cruise, or descent) unless a higher 

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