Aviation Sri Lanka 



Understanding the roles that ground facilities play during an emergency is important, but it's equally critical to be well versed in our pilot responsibilities when things are tight and help is needed. Radio failure is a great place to start, followed by an examination of other in-flight emergencies.


A potential radio failure is very hard to predict, although a thorough preflight check could give some clues. A loose or broken antenna is an obvious signal, as is a popped circuit breaker, or a loose, worn, or frayed alternator belt, if you can see or test the belt. Another clue is a radio that tends to slip in and out of its rack. Another is garbled reception on the ground or controller comments that your transmission is weak or scratchy. 

If any of these symptoms exist on the ground, the radio's either sick right now or it could die on you at an inappropriate time. The only solution is to get it fixed or the potential cause corrected before venturing forth. 

Let's assume, though, that everything checks out on the ground, so off you go. After a while, you become conscious of the fact that there hasn't been much chatter over the air for several minutes, which causes you to wonder if …  When a problem is suspected: 

•Adjust the squelch or turn up the volume. If you hear the typical static, the set's probably OK; there's just been a period of unusual radio silence. 

• Wiggle and push all mike and headset plugs to verify that they are firmly in place. 

•Check the circuit breakers. If one has popped, let it cool for a couple of minutes and then reset it. You might get your radio back, but a popped breaker is symptomatic of a problem, so have a mechanic investigate the cause when you're back on the ground. If the breaker pops out again, leave it alone; never force a breaker to remain reset. 

•Check the ammeter. If it shows no charge, test it by turning on the landing light. If the needle doesn't move, you can be sure the alternator has died or its belt has broken, in which case, the only electrical power will come from the battery. The engine won't quit, because the ignition system is independent of the alternator battery system, but without an alternator, the life of the battery is only about two hours. After that, you'll have no electrical power at all. Consequently, turn off all nonessential electrical equipment, except one radio, and head for home or the nearest airport. Enough battery power might be left to make whatever radio contacts are necessary before landing. ( most of the procedures explained above are not relevant to modern day aircrafts as they are equipped with alternative backup systems.) 

The failure is real and it's no longer a matter of suspicion: the radio is dead or rapidly dying. Now, what are your options? Five of the most likely answers depend largely on the situation. 

  1. You are flying locally or on a short cross-country away from Class B, C, or D airspace and intend to terminate the flight back at your own uncontrolled airport. Once you realize the radio is gone, the best thing to do is head for home or some other uncontrolled field where you can get the radio repaired. No need to squawk the 77001/7600 RF (radio failure) code in this environment, but do use extra caution when landing. You're coming in unannounced with presumably no knowledge of who or where anyone else is in the pattern.

 2. You are going into a Class B or Class C primary airport. To make it simple, let's say that you had enough battery juice left to monitor the ATIS and to be cleared into the TCA or to establish contact with the ARSA approach control. Once inside the TCA or ARSA, though, the radio dies completely and you have lost all transmitting and receiving contact with approach. 

At this point, squawk the 77001/7600 code and continue through the TCA/ARSA to the airport. Approach knows your intentions and, seeing the RF code on the radarscope will protect you as well as advise the tower of your predicament. 

When within the ATA, watch the tower for light signals, as summarized in FIG. 10-1, that will clear you to land or tell you to keep circling. Once on the ground, pull off on a taxiway, and continue to watch the tower for the green light that authorizes you to taxi to the ramp. 

This same scenario applies if you are transiting a Class B or Class C airspace or if you're already in one of the airspaces but intend to land at a satellite airport. The main point is to keep right on going in accordance with your announced intentions. Don't wander around in those high-density areas. If you deviate from what you have told the controller, the controller does not know what to expect, which could cause confusion in the efforts to maintain an orderly flow of traffic. 

3. You want to land at a Class D airport that has no approach control and is miles from a TCA or an ARSA. Some distance out, the radio dies, so you squawk the RF transponder code. The nearest center or approach, seeing the code on its radar, will track your flight route and, if it appears that you are headed for the controlled airport, will notify the tower of your probable landing intentions. 

As you near the field, keep a sharp eye out for the light gun signal, especially a red signal that tells you, in essence, not to land. If you see no signal, cross over the field about 500 feet above traffic pattern altitude, note the flow of traffic, fly upwind over the active runway, and watch for the green "cleared to land" signal. Keep an eye on the tower, though, even after the clearance signal. For a variety of possible reasons, you might get a red light on the final approach. Do a go-around then for another approach, as long as you get the green light again.

 4. You have not been using center or been in contact with approach, but you want to land at the primary airport in a TCA or an ARSA, and the radio has failed. Your alternative? Only one: Land outside the area and request entry approval from approach by telephone. You probably will not get it, though, unless the traffic is very light and you are close to the TCA or ARSA. Even then, the odds are against any approval without an operating two-way radio. 

5. You are on the ground at an uncontrolled field, The radio is dead, but you want to fly to a nearby Class D airport to have it repaired. Your only option is to telephone the airport tower, explain the situation, and ask for approval to enter the ATA. 

Depending on the probable traffic at your estimated arrival time, approval might or might not be forthcoming. You are on the ground and there is no emergency, so airport conditions will largely determine what the Class D tower says. In most cases, though, tower supervisors want to help, and, traffic permitting, will attempt to accommodate your request. 

Prepare with alternatives

 A VFR radio failure, when viewed objectively, is really more of a nuisance than a true emergency and should not be the cause of cockpit panic, The best advice, unless you're actually in a Class B, C, or D airspace when the failure occurs, is to land at the most convenient uncontrolled airport. 

On the other hand, if the set dies while you're in one of those controlled airspaces, stay with your already-announced intentions and proceed directly to the field. With the RF code on the radar screen, the controller will protect you from other aircraft until you are in the ATA. From that point on, the tower controller will clear you for landing with the help of the light gun.   

This procedure was introduced a long time ago and still in practice to accommodate any failure in existing radio communication system in the control tower. The signaling to the aircraft or the vehicles moving on the air field is done by 3 color lamp called "Light Gun". Following table explains the specific information provided by color pattern.

Color and
Type of Signal

of Vehicles,
and Personnel

 Aircraft on
the Ground

in Flight

 Steady green

Cleared to cross,
proceed or go

 Cleared for takeoff

 Cleared to land

 Flashing green

Not applicable

Cleared for taxi

 Return for landing
(to be followed by
steady green at the
proper time)

 Steady red



Give way to
other aircraft and
continue circling

Flashing red

Clear the

Taxi clear of the runway in use

Airport unsafe,
do not land

 Flashing white

Return to starting
point on airport

Return to starting
point on airport

 Not applicable

Alternating red
and green

Extreme Caution

Extreme Caution

Extreme Caution

Quite apparently, you and I have to know what those on the ground expect of us when we are faced with a radio failure, otherwise, we could be guilty of causing a lot of confusion and perhaps hazardous conditions for others and ourselves. The only answer is to be prepared for the problem and have a clear set of alternative actions in mind if the problem should ever become a reality. 

Another aid in attracting attention to an aircraft in distress and its need for help, is "chaff." This consists of a small packet of strips of coated material, usually aluminum foil, If unable to communicate, a pilot should fly a straight course, dropping a box of chaff every two miles until four packets have been dropped. Then, continuing on the same straight course for two miles, he should make a 360- turn to the left; another two miles and another 360' turn to the left, and so on until four 3600 circles have been flown. This total pattern (four drops of chaff and four 360' turns at 2-mile intervals) increases the probability of detection by the radar controller-and of the assistance needed. 

The same constant direction of flight should be maintained after the total pattern is completed, so that ground personnel may have continuing information as to the position of the aircraft in order to provide help. Since the dropping of chaff temporarily prevents the functioning of radar for its normal uses, it should never be used except in case of genuine distress or upon direction by the ground station. 


The FAA makes it very clear that when an emergency develops while in flight, only one person has the final responsibility for the operation of the aircraft. That person is the pilot. The FAA further makes it clear that rules and regulations are pretty much tossed aside when action is required to meet the emergency. In the process, however, the FAA stresses that the pilot should request immediate help through radio contact with a tower, a center, or a flight service station. 

Emergency classifications 

Emergencies are classified as distress or urgency. A distress condition is one of fire, engine failure, or structural failure. In other words, the situation is dire, immediate, and life-threatening. Urgency is not necessarily immediately perilous but could be potentially catastrophic, as being lost, a low fuel supply, a seriously malfunctioning engine, pilot illness, weather, or any other condition that could affect flight safety. When any of these conditions arise, the pilot should ask for help now, and not wait until the urgency becomes a distress. 

While AIM outlines the appropriate emergency procedures in some detail, the following summarizes the essential elements for the VFR land pilot. 

Transponder operation 

This I've touched on before, but when either an urgency or a distress situation develops, immediately enter the 7700 emergency squawk in the transponder. That code then appears on the screens of all radar-equipped facilities within radar range and, by sound as well as the flashing blip, attracts the controllers' attention. As controllers put it, "lights light and bells ring." Ground help is, of course, hard to offer if the pilot has not been in contact with a center or any other facility, but at least they know that there's an aircraft in trouble out there and they know its location. 

Radio communications 

Whether you dial in 7700 or call a ground facility first is a moot point in a distress condition. Unless you were already tuned, let's say, to a center, it might be better to squawk the code immediately and then change the radio to center, approach, a tower, or an AFSS. If you don't have time to search for one of those frequencies, always remember 121.5. This is the emergency-only frequency that is guarded by direction finding stations, civil aircraft, centers, military towers, most civil towers, and FSSs. 

When faced with a distress condition, start the radio call with "Mayday" repeated three times. This is the universal call for assistance and comes from the French, "M'aidez," pronounced "Mayday," meaning "Help me." Distress messages have priority over all others, and the word "Mayday" commands radio silence on the frequency in use. 

In an urgency condition, begin the call with "Pan-pan" repeated three times. Urgency messages have priority over all others except distress and warn others not to interfere with the transmissions. 

Recognizing the problem of time limitations in an emergency situation, the FAA suggests that as much of the following as possible be communicated, preferably in this sequence: 

1."Mayday, Mayday, Mayday" or "Pan-pan, Pan-pan, Pan-pan"

2.Name of facility addressed

3.Aircraft type and identification

4.The nature and of the distress and type


6.Pilot’s intention request

7.Present position and heading, or it' lost, last known position, (line, and heading since that position

8.Altitude or flight level

9.Hours and minutes of fuel remaining

10.Any other useful information, as visible landmarks, aircraft color, emergency equipment on board, number of people on board

11.  Activate the emergency locator transmitter (ELT) if possible 

Pilot responsibilities after radio contact

Once in contact with a ground facility, a pilot has certain responsibilities:


Maintain control of the aircraft



Comply with advice and instructions, if at all possible 






Ask questions or clarify instructions not understood or with which you cannot comply



Assist the ground facility in controlling communications on the frequency. Silence interfering stations.



Don't change frequencies or change to another ground facility unless absolutely necessary,



If you do change frequencies, always advise the ground facility of the new frequency and station before making the change.



If two-way communication with the new frequency can't be established, return immediately to the frequency where communication last existed.



Remember the four Cs:

            Confess the predicament to any ground station;

            Communicate as much of the distress/urgency message as possible;

            Comply with instructions and advice;

            Climb, if possible, for better radar detection and radio contact.



Emergency locator transmitters, designed to assist in locating downed aircraft, are required by FAR 91 for most general aviation aircraft, although certain exceptions are allowed. An ELT is a battery-operated transmitter that, when subjected to crash-generated forces, transmits a distinctive and continuous audio signal on 121.5 and 243.0. The life of a transmitter is supposed to be 48 hours over a wide range of temperatures. 

Depending on its location in the aircraft, some ELTs can be activated by the pilot while airborne. In other installations, the ELT is secured elsewhere in the fuselage and cannot be accessed in flight. These are activated only upon impact or by the pilot when on the ground and out of the airplane. 

Because of their importance in search and rescue (SAR) operations, ELT batteries are legal for 50 percent of their manufacturer-established shelf life, after which they must be replaced. Periodic ground checks of an ELT should be made, but only in accordance with the procedures outlined in AIM. 

Anticipation and alternatives 

Although this discussion of emergencies is necessarily limited in scope as well as depth, one pilot responsibility hopefully stands out: the responsibility to be prepared mentally and physically for the unexpected, the nonroutine. If you fly long enough, sooner or later you're going to encounter an emergency situation of some nature. Perhaps it will be very minor and easily correctable; perhaps it will require every bit of knowledge and expertise you have amassed. Whatever the case, the odds of something going sour sometime are close to 100 percent. 

If that's a reasonable bet, preparation (and all that preparation implies), is absolutely essential. Beginning with every pilot's very first flight, they ought to be asking two questions: "What could go wrong? If 'what could go wrong' did go wrong, what would I do?" As suggested elsewhere in the book, this is the process of potential problem analysis (PPA). 

A fire in flight; the engine bucks and coughs for no apparent reason; the engine quits entirely; a bird strike smashes the windscreen; a passenger has an apparent heart attack; you're lost; the fuel gauges are showing close to empty; electrical power is interrupted: What would you do? It's a matter of anticipating these as well as other potential problems and then having alternative plans of action firmly in mind in case a potential ever became a reality. (As always, above all else, fly the aircraft first, then follow through with your planned and alternative actions.) 

While transponder and radio procedures are perhaps only small elements in handling a distress or urgency situation, they could be major factors in helping you get that airplane down safely and in one piece. Our entire ATC system is designed to maximize safety, and the folks on the ground have had drilled into them what to do when a pilot calls Mayday or Pan-pan or squawks the emergency or RF code. But controllers can only help pilots to the extent that pilots can help controllers. That's where personal preparation and the skill with which pilots handle the emergency, comes into play.