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Pilot/Controller Glossary 

6/17/21 

These notices can be found on the International 
Notices website. 

INTERROGATOR

 The ground-based surveillance 

radar beacon transmitter-receiver,  which normally 
scans in synchronism with a primary radar, 
transmitting discrete radio signals which repetitious-
ly request all transponders on the mode being used to 
reply. The replies received are mixed with the 
primary radar returns and displayed on the same plan 
position indicator (radar scope). Also, applied to the 
airborne element of the TACAN/DME system. 

(See TRANSPONDER.) 
(Refer to AIM.) 

INTERSECTING RUNWAYS

 Two or more 

runways which cross or meet within their lengths. 

(See INTERSECTION.) 

INTERSECTION

 

a. 

A point defined by any combination of courses, 

radials, or bearings of two or more navigational aids. 

b. 

Used to describe the point where two runways, 

a runway and a taxiway, or two taxiways cross or 
meet. 

INTERSECTION DEPARTURE

 A departure from 

any runway intersection except the end of the runway. 

(See INTERSECTION.) 

INTERSECTION TAKEOFF

 

(See INTERSECTION DEPARTURE.) 

IR

 

(See IFR MILITARY TRAINING ROUTES.) 

IRREGULAR SURFACE

 A surface that is open for 

use but not per regulations. 

ISR

 

(See INCREASED SEPARATION REQUIRED.) 

PCG I