It is important to remember that it is often difficult to diagnose radio malfunction during flight.
Therefore it is hard to know whether you have a malfunctioning transmitter, a malfunctioning receiver, or perhaps both.
You also have the point-of-failure that is the headset you are using.
For this reason it is quite usual to carry a spare headset and the first piece of diagnostics is to swap headsets.
Many General aviation aircraft also have a handheld microphone and speakers integrated into the radio stack.
Once you've ascertained that its the actual transmitter and/or receiver that has failed it is common to set the transponder to 7600.
For landing, the relevant detail for the procedure to follow is contained within Chapter 4, Section 2-13 of the AIM : Receiver Inoperative Remain outside class D airspace until the direction of air traffic can be ascertained Notify the tower
your type, position, altitude, intention to land and request
you are controlled with light signals At 3 -5 miles, advise the tower of your position and join the traffic pattern Watch
the tower for light signals Continue to advise of position (downwind, turning base, etc)
Transmitter inoperative Remain outside class D airspace until the direction of air traffic can be ascertained
Monitor the primary local control frequency as depicted on sectional charts for landing or traffic info.
Look out for light signals that may be directed to your aircraft During hours of daylight, acknowledge tower transmissions or light signals by rocking your wings At night, acknowledge by blinking landing of navigation lights Transmitter & Receiver inoperative
Remain outside class D airspace until the direction of air traffic can be ascertained Maintain visual contact with the tower and acknowledge light signals as above.
The light signals used for an aircraft in flight are as follows source : Steady green - Cleared to land Flashing
green - Cleared to approach airport, or return to land Steady red - Continue circling, give way to other aircraft Flashing red - Airport unsafe, do not land Alternating red and green - Exercise extreme caution
They can be seen in this video .
aviation.stackexchange.com/users/100/Jamiec
First thing you do when the radio breaks down is to start squawking 7600
(the code for radio malfunction) on your transponder.
Then when you approach the airport they will attempt to contact you first through radio (to see if you can still hear them) and you use alternate means of replying (sending IDENT on transponder, rocking your wings,...).
If you can't hear them they will use a light gun to convey messages.
aviation.stackexchange.com/users/609/ratchet freak
Ratchet Freak has a good answer.
In addition, please pull out your cellphone and try calling the tower .
Somewhere in the bottom of my flight bag I have a small book with telephone numbers at towers.
If you don't have that, call Lock-Mart Flight Service at 1-800-wx-brief
tell him you need the tower number.
Also remember that there is no requirement for a radio in an airplane.
NORDO (No Radio)
aircraft are perfectly legal although in practice, they operate mostly out of non-towered fields.
Operating out of a towered airport is still possible, but it requires prior coordination with the tower.
Note
please that flight in the SFRA around Washington DC does require a radio, and I have seen no procedures to allow for NORDO aircraft in this area.
If your radio stops working, one option is to fly to a non-towered field and do what the NORDO planes do:
Overfly the field at a safe altitude, note wind direction from the wind sock or tetrahedron, note other traffic in the area, and fit yourself into the traffic pattern... and land.
aviation.stackexchange.com/users/291/Skip Miller
I was a Junior Technician, later Corporal, Air Wireless Fitter in the R.A.F. in 1952-4, servicing Gloster Meteors' radios at a Flying Training School, and the signal then was for the pilot to waggle the aircraft's wings as he approached, or flew by, on his way to land, to show he could not contact the Control Tower.
Then we had to fix it.
I was made a Corporal so that I could sign off our work on the aircraft out on the airfield, usually just tuning up to a new crystal to suit the frequencies of a distant Station.
I got the promotion so the Sergeant could stay in the nice warm office
: I didn't mind -- I was "/Paid
" extra, nice for a "National Service
Only" erk.
Happy days
aviation.stackexchange.com/users/2312/Harry Weston
The NORDO procedures are covered extensively in the AIM.
That is suggested reading for any pilot.
Cellphones are unlikely to work airborne, except close to the ground, and then in remote areas.
Most cell systems will ignore a phone which brings up many towers, thereby preventing it from calling.
Text might work better.
Most pilots don't frequently call towers, but it is worth noting that many times the tower will not answer the phone, depending upon workload.
Calling FSS might work better, and they have more direct access to the tower through multiple means.
Many pilots carry a small transceiver, which is a good backup device.
I use mine to get ATIS and Clearance prior to engine start.
At least that way
I know it is frequently working.
A final point, if you do loose transmit capability, listen on the last frequency you were talking on.
They will probably try to contact you, and you may likely get walked through communications changes until you are on the ground, listening only.
That has happened to me.
The radios lost transmit capability due to a failure in the audio panel.
Center handed me to approach, who vectored me to the ILS, and gave me a frequency change to the tower.
Tower gave me taxi instructions.
There was no need to transmit.
No need to use a cellphone or anything else, and no need to dig out a backup radio.
But the starting point for understanding the procedures is to visit the AIM.
https://www.faa.gov/air_traffic/publications/media/aim.pdf
aviation.stackexchange.com/users/18572/mongo
Is there a special protocol for a situation where the on-board radio communication equipment suddenly breaks down? Would the pilot be able to land on a busy towered airfield or would they be forced to look for a small landing strip in the middle of nowhere?
How would an airplane land if the on-board radio breaks down?
aviation.stackexchange.com
<landing><emergency><radio-communications><lost-communications>
aviation.stackexchange.com/questions/3794
aviation.stackexchange.com/users/2172/JonathanReez
If the transmitter has failed, it is usual to set the transponder to 7600. NORDO procedures for landing without communication are covered extensively in AIM. The aircraft should remain outside class D airspace until the direction of air traffic has been ascertained and local control frequency should be monitored. Some pilots carry a small transceiver as a backup device. Once you know that it is the transmitter and/or receiver that is not working, you would normally set the transponder to 7600. If the transmitter is not working: stay outside class D airspace until it is possible to identify the direction of traffic.  Monitor the primary local control frequency as shown on the sectional charts. The procedure used to be for the pilot to waggle the aircraft's wings as he flew by or approached. This would show the control tower that he was unable to contact them. There is extensive coverage of the NORDO procedures in the AIM. Cellphones are unlikely to work while you are in the air unless you are close to the ground in a remote location. Most pilots do not often make calls to towers but you should bear in mind that the phone will often go unanswered at the tower depending on how much work they have to do. Many pilots have a small transceiver, which is a good backup device.
Once you know that it is the transmitter and/or receiver that is not working, you would normally set the transponder to 7600. If the transmitter is not working: stay outside class D airspace until it is possible to identify the direction of traffic.  Monitor the primary local control frequency as shown on the sectional charts.  The procedure used to be for the pilot to waggle the aircraft's wings as he flew by or approached. This would show the control tower that he was unable to contact them. There is extensive coverage of the NORDO procedures in the AIM. Cellphones are unlikely to work while you are in the air unless you are close to the ground in a remote location. Most pilots do not often make calls to towers but you should bear in mind that the phone will often go unanswered at the tower depending on how much work they have to do. Many pilots have a small transceiver, which is a good backup device.