Originally Posted by
Irishwingz
Some military aircraft have homing beacons,
Dedicated Search and Rescue Dedicated Search and Rescue aircraft have homing
receivers that can be used to home on VHF or UHF beacons.
I am not sure if these work at the bottom of a deep ocean.
They don't, but dedicated anti-submarine aircraft and other dedicated platforms my drop hydrohpones that can detect sonic transmissions.
Is it surprising that large commercial aircraft do not have such devices, especially when operating in areas of non VHF & radar coverage?
No, it would cost money, lots of money, to install such homers in many aircraft. The use of such homers would then require crew training which would increase training time, working hours, require more aircrew etc etc.
However all aircraft are capable of localising a VHF or UHF beacon but they need lots of spare fuel to do so. The technique is simple but I shall not post it here.
PS
FE Hoppy said some mil ac have ULF Homers and no training is needed. I would suggest that some training would be needed but concede it might not be very much. Equipment costs however would remain a significant hit on the bottom line.