Mode Question, Please

[BOBRR]

Hi,

Just getting back into hobby.

Could you please verify for me that 121.5, the Aero. Emerg. frequency, is AM ? Always ?

Thanks,
Bob

 

[andy51edge]

Hi,

Just getting back into hobby.

Could you please verify for me that 121.5, the Aero. Emerg. frequency, is AM ? Always ?

Thanks,
Bob

Yes sir! Always AM. Every aircraft that I have flown only had AM radios, I have never had the option to go to FM.

 

[tvengr]

It is my understanding that aircraft use AM because of the FM capture effect. If 2 aircraft should transmit at the same time and one is stronger than the other, the stronger signal will capture the discriminator of a FM receiver and the weaker signal will not be heard at all. Air traffic control would not know that 2 aircraft were transmitting.