IFF Check – Squawk Three

by Lt. Col. (then Captain) John Larrison (USAF Ret)

In the 1960s the jet powered T-33 (T-Bird) was used as the training aircraft in basic training following primary training in the reciprocating engine T-34 & T-28. To better understand the Identification, Friend or Foe (IFF) check as a T-33 pre-solo requirement, you might want to read the story of the primary pilot training requirement for a radio Direction Finder (DF) steer prior to T-34/T-28 solo. This was a VHF radio procedure where a control tower direction finder would “home” on the students transmitted radio signal. To get a better radio signal for a more precise heading, the control tower would ask the student pilot to “Growl” during the radio transmission.

 Now, fast forward to Basic Pilot Training and the T-33. Radar was replacing the radio DF procedures. In those years most military jet aircraft were equipped with a very basic Identification, Friend, or Foe (IFF). At that time the IFF only had three basic modes of operation: Mode 1, Mode 2, Mode 3, plus an emergency mode. Current Transponders (IFF) have added Selective Identification Feature (SIF) to provide numerous codes to identify and track aircraft. A ground radar controller can request an aircraft to set in a specific mode and code for identification and tracking. This was known in Air Force terms as “Squawking” because the IFF is known as a parrot. Get it — parrot, squawk ?

Now our student pilot has completed primary pilot training in the T-34 & T-28 and is about to solo in the T-33. In this case he was one of my “Table Mates” who shall remain nameless. There were normally three students per instructor. Today he was scheduled for his pre-solo flight with our instructor. 

Prior to departing for the flight, he asked me, “how do you do one of these Parrot Checks?” The Devil made me do it, but I just couldn’t pass up the situation. I told him it was a simple check much like we did in primary during a DF Steer. In this case, you selected the radio frequency of the nearest ground radar site (which we had in our training area) and ask for a “Parrot Check.” They could then identify you on their radar scope and give you a heading to your destination. In this case Home Base, if you happened to be lost.

To accomplish the Parrot check, they would request you to “squawk” one of the three available modes. The correct procedure would be to set in the requested Mode, they would identify your radar return, and give you a heading to home base. But being the joker I was, I told him that it was just like we did in primary training. In this case you go to the radar site radio frequency, establish contact, and request a Parrot Check. They will respond by asking you to turn your IFF on and Squawk one of the three available modes. Then if it was Mode Two, you press the mic-button on the radio and in a loud voice say, “ Squawk, Squawk.” If Mode One was requested, you would only respond with one “Squawk.”  And that’s what he did on this pre-solo flight! 

Needless to say this was a great embarrassment to his instructor pilot. As I said in the beginning, he was also my instructor pilot. So, as you can guess, this joke did not “improve” my student/instructor relationship for a few weeks. But it provided one hell of a good laugh for some of us!