ILS freqs for PWM are the same for both approaches?


Admittantly my instrument flying is limited. I fly as much as possible but suppliment some flight sim time on the PC fo procedures. I always look for areas of bad WX and will pick a short cross country. Tonight I decided to go from LCI to PWM. I downloaded the PWM plates and noticed the ILS freq’s are the same for both ends.
Is this unique? In my instrument flying experience the only time a freq might be the same is if it’s a back course. These ILS’s have different morse code identifiers but share 109.9.




This is quite common.

It is the OBS heading that is the key factor here. Those should be the exact opposite from eachother.

Take into account, ILS 24R at KLAX. Both use the same frequency of 108.5, whereas the OBS heading is 249 for 24R, but 069 for ILS 6L. Both use different LOC identifiers and Morse Code identifiers, but the frequencies are the same.



It saves on frequency congestion.
If they are landing on 29 a switch in the tower is set one way but if the wind switches to the east a simple flip of said switch turns off the 29 ILS and turns on the 11 ILS.
The frequency is the same for the back course because it is the same transmitter as the front course.

John in Saudi


Thanks guys, interesting. All of the approaches I flown (which is a limited number of airports) have been at airports that have different freqs for each, I’ve never seen this before. It makes sense to do it. just never occurred that they could.