An Interesting ASRS Report
I lost radio contact with Tower. By accident my daughter disengaged my hand-mike jack from its receptacle enough to cut off communication, but I could not tell. She was in right front seat with a blanket over her legs that prevented my noticing anything wrong. After landing I discovered the problem and contacted Ground Control for taxi instructions. Tower said they gave me a red signal when our communications went out, but unfortunately I did not see it.
Moral: If you are NORDO (no radio) near a controlled airport, keep a sharp eye out for lightgun signals. Even in this high-technology era you sometimes have to fall back on the old reliable methods.
ASRS Report
When radios stop working, tower controllers fall back on a primitive but effective means of communication to control traffic in the landing pattern - light signals. These signals are shown in Figure 37. Holding a small but powerful light gun (Figure 38), controllers can direct a concentrated beam of light directly at your aircraft. Using one of three colors - red, green, white - controllers can communicate several important commands to pilots.
Light Signals in the Air - If your radio fails under VFR conditions, simply enter the traffic pattern at a tower controlled field after observing the flow of traffic (not going with the flow could result in a few unusual signals from the pilots in the other airplanes). Keep an eye on the tower cab for a light signal. If, while airborne, you receive a steady green light, this means you are cleared to land. Think of a steady green light as being similar to the three green landing gear lights on a retractable geared airplane. If they're all indicating green, then it's OK to land.
If you saw your three green landing gear lights flickering or flashing instead of painting a steady green, you'd probably go around and solve the problem. Likewise, a flashing green light from the tower means you should return for landing, to be followed by a steady green light at the proper time. This is essentially a go-around command.
A steady red always means stop. At least that's what it should mean to you at a stoplight. Of course, the only way to stop in the air is to give way to other aircraft and continue circling. Controllers might use this signal if they see you (a non-radio airplane) approaching the traffic pattern and are unable to sequence you into the flow of traffic. They'll hold you in your present position until they can clear you to land. At that time you'll probably receive a steady green light.
Whenever you see a flashing red light in the air, it indicates danger. Think of all those red flashing beacons you see on tall TV towers. Tower controllers send out a flashing red light when the airport is unsafe for landing. The runway could be torn up, there could be a disabled plane on the runway, or perhaps there are deer and antelope at play. Whatever is wrong, the controller is telling you that bad things will happen to your good airplane if you land there. It's time to head for the next closest airport.
Alternating red and green lights, on the ground or in the air, mean exercise extreme caution. There might be another no-radio airplane in the pattern. Or, there might be wild animals running across the runway. Don't think that this can't happen. A fellow pilot in Florida had an alligator crawl onto the runway during landing. I'm not sure what would happen if you hit one of these big guys. Perhaps you'd leave a trail of boots, assorted baggage and Gucci belts scattered along the runway.
Light signals also apply to surface movement at tower controlled fields. Radios do go on the fritz occasionally, though many general aviation airplanes have a double set of communications radios. If there is no avionics repair shop at your home field, you'll need to fly somewhere to get it fixed. If you have no communications capability, simply call the tower by phone and tell them you want to depart the airport. They'll probably tell you to taxi out and visually monitor the tower for light signals.
Light signals also serve as your taxi instructions after a no-radio landing.
Light Signals on the Ground - A steady green light on the ground means the same to an airplane as it does to a car - go. A steady green light means that you're cleared for takeoff (in your airplane, not your car). A flashing green light on the ground means that you're cleared to taxi. If you look in your rear view mirror and see a steady red light you'd better stop. It's the law and they want to talk to you. Similarly, a steady red light from the tower means you should stop. The controller wants you to hold your position. When the time is right, they'll provide you with a flashing green signal to continue taxiing.
A flashing red light in your rear view mirror usually belongs to an emergency vehicle. Your natural response in a car is to get off the road. In an airplane a flashing red light from the tower is a signal to taxi clear of the runway in use. You might have just landed without a radio and are taxiing down the active runway. The controller may have another airplane waiting to land. A flashing red light is a signal to clear the runway on which you've landed. Simply find the nearest taxiway and get on it.
The last light signal is the flashing white light. It only pertains to operations on the surface. If the airport suddenly becomes very busy, your no-radio takeoff might be more appropriate at a later time. Controllers will signal their desire to have you return to your starting point on the airport with a flashing white light. Think of the newer automobiles that have flashing headlights to warn you that you must return to your starting point to turn them off (my original car had headlights that flashed, not because of new technology, but because of a bad circuit. It did have a heated rear window that kept my hands warm on those cold days when I had to push it in for repairs).
For more information on this subject, see "Embraced By The Light."
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