Instrument Insights Part 10 of 12

Too Quiet in the Cockpit

October 1, 1998

Nothing to say, lots to do

Imagine yourself in the clag. You have the weather well mapped out, thanks to onboard storm-avoidance gear and a good preflight briefing. The air is surprisingly smooth, and there's no ice. The engine plays along, a familiar drone ahead of the windshield. The autopilot is flying the airplane with uncharacteristic smoothness. All is well in the land of IFR flying.

Then you realize that the chatter on center frequency is missing. You wonder briefly, "Is it me, or just a shift change?" Instinctively, you pull the squelch knob or hit the test button. Static, just as you'd expect. You switch to com number two to hear the controller calling your tail number. You respond, but it's clear that the controller can't hear you. A flash of "uh-oh" crosses your mind. You are now in the land of the lost communications.

Indeed, there are many levels of being incommunicado. Perhaps the most benign is loss of transmitting or receiving capability on the main coms. Further down the terror chain is the loss of basic navigation and transponder equipment, followed by a complete electrical failure that renders all electronic components mute. There are, however, ways to deal with all of these situations.

During instrument training, the concept of lost communications is often given little emphasis. "Read over FAR 91.185 for the test and the oral," you might hear, but it's unlikely that you'll practice lost-com procedures during training. So when it does happen — usually, as the gods of instrument flying demand, when you've got plenty else to do — the procedures recede into distant, inaccessible memory.

Not to worry. The best lost-com procedures are the simplest. Follow us through a bit of troubleshooting.

Once you realize that you're out of touch with ATC, don't panic. Fly the airplane and continue to navigate. Determine the nature of the problem. Can you hear but not talk? Before you jump into emergency mode, wait. See if you might just be out of range of ATC's radio web. (It happens more often than you might think, particularly if you're flying at the minimum en route altitude in mountainous locales.) The controller has more than one repeater station, so give him a chance to switch to one that might be able to pick up your transmitter. You might also be asked to squawk ident if you hear the controller. Doing so, which lets the controller know that you can still hear him, will probably start a primer on what he's planning for your lost-com handling.

Naturally, try the other radio before you slide 7600 into the transponder. Double radio failures are rare, but total lost com because of some common element, like an intercom, push-to-talk switch, or audio-selector panel, is possible. Are you getting side tone — the sound of your own voice when you transmit — in your headset? If not, start thinking that you have a microphone problem. Pick up and try the hand mic — you do have it in easy reach, don't you? Try another headset. Check the intercom settings and jiggle the audio panel's transmit-select switch. If the com radio has a transmit indicator, see if it's illuminating when you punch the PTT; also listen for a "pop" when you key the mic. If you don't see the light or hear the pop, you have some sort of keying problem. Again, keep listening for the controller's directions.

You should start unpacking the portable transceiver from the gear bag about now. Few pilot doodads are as useful as a handheld com when you've lost the ship's systems. Keep in mind, however, that the range of a small, battery-powered transceiver is severely limited without an outside antenna; so much so that you might not be able to reestablish communications with a center or approach-control facility unless nearly on top of the facility's antenna. Even so, the receiving performance of most handhelds is sufficient to listen for ATC's calls, even if you can't respond.

So the external antenna is a must. Contact your radio shop for the best solution. Bendix/King made a small box that could be spliced into one of the com's antenna leads for emergency use; inserting the handheld's connector into the box disconnected the panel-mounted radio from the line. (You don't want to transmit into the antenna with the onboard com radio on the line; you'll damage its transmitter section.)

For renters, take a trip to the local Radio Shack for a device that is, essentially, a short length of coaxial cable with a small bracket and a suction cup. This will allow you to remote the antenna to a side window and free you from having to hold the radio up above the instrument panel to talk — it may not be enough to let you talk with ATC, but it's better than having to fly with one hand and juggle the handheld with the other. A headset adapter for the handheld completes the picture here. And it won't hurt to have a spare set of alkaline batteries handy to feed the handheld transceiver; nicads have poor shelf life compared to alkalines, making them less than ideal for standby use. Remember to plan ahead to make life easy for yourself when the radios do quit.

And what if you discover that you can't receive but can transmit? Again, try the various combinations on the audio panel and intercom to see whether it's possible that you might have just flipped the wrong switch. Try the cabin speaker, too. The point is this: Take a few moments to positively determine that you have had a radio failure by eliminating the simple problems first.

Once you've determined that you have a bona fide radio failure, start implementing your escape route. Punch 7600 into the transponder for one minute, then return to your assigned code — unless, of course, you can hear ATC and it's been determined by the man behind the scope that you are unable to transmit. FAR 91.185 says, basically, that if you're in VFR conditions when the failure occurs or if you encounter good weather afterward, you should continue the flight under VFR to a landing "as soon as practicable." Does this mean that you should plop down at the nearest airport or continue to your destination? Depends.

If you can get the word to ATC that you are canceling IFR — plugging 1200 into the transponder isn't enough — you can continue on your way VFR. Understand, though, that until you cancel or call safely on the ground, ATC will clear a path for you all the way to your filed destination or clearance limit. It's imperative that you let them know you can cancel IFR if you're continuing VFR. If you can't, then land right away and get ATC (or a tower, or flight service) on the phone as soon as you land.

At the other extreme, when the weather is really junky and you know that an instrument approach will be required in order to get down, you're better off continuing on to your destination as per the filed flight plan. FAR 91.185 says, in part, "If the failure occurs in IFR conditions…each pilot shall continue the flight…by the route assigned in the last ATC clearance received; or, if being radar vectored, by the direct route from the point of radio failure to the fix, route, or airway specified in the vector clearance." You are expected to remain at your assigned altitude, unless a part of the route has an MEA higher than the assigned altitude; then you are expected to climb to the MEA.

Should you, after traversing the segment whose MEA is higher than the last assigned altitude, return to the assigned altitude? As a practical matter, controllers say that as long as your transponder is working, it doesn't really matter. When they see you descending back to the assigned altitude, they'll clear the way; but they won't lose sleep if you stay where you are. There are exceptions. When you are entering highly congested airspace, it's possible that remaining at the nonassigned altitude will conflict with a conga line of jets. Even if you are on a clearance that you know will be changed, stay with the last assigned or "expect further" clearance. That's what ATC will be expecting you to fly, even if it will conflict with air-carrier traffic. Again, because of the ripple effect within ATC of clearing the way for you, it is critical that you don't make the controller think, "What's he doing now?"

When you arrive near the destination, the rules say that you should depart the clearance limit at the estimated time of arrival. Does this mean that, should you arrive early, you ought to fumble through the holding procedure until your time is up? Although that's the way the rule is written, the controllers we know say that they would prefer that you begin the approach when you arrive at the fix. The logic is simple: The more time you spend IFR in controlled airspace, the more trouble it is for ATC. Get on with it and put yourself on the ground.

It's the in-between flights that are hard to judge. Don't punch out of the IFR system to scud run. Be sure that once you opt for the VFR letdown you'll be able to complete it successfully. It's best that you formulate a plan and stick to it, rather than waffle. Consistency is the controller's best friend in times like these.

Tip sheet

  • Try the radios occasionally, in case the problem is intermittent, as could be the case with a heat-related failure. If you do regain contact with ATC, fess up to the problem and let the controller know that you might lose contact again. Start working on a weather picture that'll put you into VFR conditions in a reasonable amount of time.
  • Monitor the rest of the electrical items carefully. One of the most common causes of lost communications is an alternator failure and subsequent battery depletion. The high-current items will be among the first to object to reduced system voltage. Keep the ammeter or voltmeter in your normal scan. At the first sign of electrical trouble, reduce the load by turning off unneeded instruments and lights and advise ATC immediately that you are on battery power only.
  • Consider keeping a portable GPS at the ready. Even the most basic unit will help you to devise a route home or to reported VFR weather when all else has failed.
  • Maintain situational awareness. If you know where you are when the radios go dead, you'll have an easier time constructing an escape route.

Links to all Web sites referenced in this issue can be found on AOPA Online. E-mail the author at marc.cook@aopa.org.