Aircraft Operations Commentary

General Information for Aircraft Operation


An emergency locator transmitter (ELT) is a box containing a transmitter, a battery, and a G-switch. On the side of the box is a manual switch with three positions, on, off and armed. If the switch is in the off position, the box doesn't do anything. If the switch is in the armed position, and the ELT is subjected to a 5 G force such as might be experienced during a crash, the G-switch activates the transmitter, sending a distress signal on 121.5 MHz. The external toggle switch does not move in a crash, but the ELT is on, internally. If the switch is turned to on, the ELT immediately sends the distress signal, with no need for a violent force.

If you require rescue, turn your ELT switch to on immediately, and leave it on until the rescuers tell you to turn it off.

Jet and Propeller Blast

Propellers and jet engines accelerate a volume of air behind them. Even at idle power, the blast may be dangerous to people, vehicles and other aircraft.  To work safely around jets, you need to know that they can blow you away like a tumbleweed, so don't even think of taxiing behind one. For the PSTAR, however, you need to know some specific numbers. This is the relevant page from my A.I.P. Large: 600'/1600'  Medium: 450'/1200' Small 200'/500'
The numbers circled in red are all answers to questions on the PSTAR.  No questions ask about the other two. To remember this with the least effort, think "2-4-6" for the ground idle danger zones (from small to large) and triple them for the take-off thrust danger zones. That's not exact, but if you can remember it, the closest PSTAR answer will be right.

If you would like to read some stories of jet blast damage, see this US Government report. A large jet turning around at the gate can blow over a twin engine commuter airplane.

Jet blast is caused by the engine, and is present only while the aircraft is there, running its engines.  It is not the same thing as wake turbulence, which is only present in flight.

VDF Steers

Some ATC units have the equipment to detect your bearing from the control tower, based solely on your radio transmission. If you are in difficulty, you call them on a particular frequency and ask for a "VDF steer." They will ask you to key your microphone (hold down the transmit switch) for several seconds, and then they will give you a bearing to fly to reach the airport. It is still your responsibility to remain VFR and avoid obstacles and other traffic. But if you're really lost, like the pilot in this joke, ATC will be happy to help.

Question-by-Question Explanation of Aircraft Operation

(1) The sooner you turn the ELT on the more quickly help will come. Once it has been turned on it may take some time for your signal to be pinpointed. Turning it on and off could delay that process.
(2) Flight Services will start calling around to look for you after you are overdue on your flight plan, but that could be hours after your emergency. Satellites and other commercial traffic are already listening on 121.5. Don't wait!
(3) An ELT may be tested during the first five minutes of any hour, but not for the whole five minutes, just for five seconds.
(4) If satellites have located your ELT signal, there may be a search and rescue team on its way to find you, even in the dark. Don't turn your ELT off until the SAR personnel tell you to.

(1) It could turn on accidentally after a hard landing, but you can use your radio to check it, and then go to the ELT itself to turn it off if necessary.
(2) CARs 605.40 tells you when you may or may not activate your ELT.
(3) It's not a bad idea to test the ELT after a component change, but this answer is incorrect because you must wait until the first five minutes of the hour. You can't just test it anytime.
(4) When you turn on the radio and listen on 121.5 you are listening for an ELT signal, not activating your ELT.

(1) Don't turn your ELT off at the end of the flight. You need it to be armed in case of an emergency. After maintenance, check the box to see that the mechanics did not turn it off. They sometimes do.
(2) If you hear a signal on 121.5, turn your radio to an adjacent frequency. If you still hear the signal on 121.55 or 121.6, the ELT signal is originating from somewhere very close by, and might be yours.
(3) The ELT has its own battery and will continue to signal whether the master is on or off.
(4) There usually is no visual warning light on an ELT. That would make it cost more, and be something else to go wrong.

If your ELT goes off accidentally, turn it off immediately and call the nearest air traffic services unit. After you have switched it off, you can turn it back to armed.

(1) The pilot doesn't necessarily have to be the one who remains with the aircraft.
(2) CARs 602.10 says the aircraft must be attended, but it doesn't say by whom.
(3) The size of the airplane is not mentioned in this regulation.
(4) Control locks prevent damage to the airplane. This rule prevents damage to people who might be hit by a runaway airplane.

11.06 & 11.07
Thunderstorms are associated with very strong, rapidly shifting winds, and downdrafts. Large passenger jets have crashed on approach when they could not maintain altitude against the downdraft or windshear from a thunderstorm. The effect exists underneath a thundercloud and up to 20 miles away, even if it is not raining or is raining only lightly. The best approach is to wait until it has passed before landing.

See the general information on this section for tips on remembering these distances. But think about how large they are. According to the numbers in the A.I.P., if a Boeing 747 were do do a full-power run up at one end of an aircraft carrier, it could blow sailors overboard at the other end of the ship, because that would still be within its 1200' danger zone.

For those of you in the Vancouver area, 600' would blast right across the domed Stadium at BC Place.

If you're crossing the street, do you notice what kind of traffic is at the intersection one block away? You'd better be looking that far if you're taxiing behind a medium jet at ground idle power, because its danger zone is 450', the length of a city block.

Two hundred feet is the length of a hockey rink. That's how far you must be behind an executive jet, like a Lear, stopped on the ground with its engines running. Allow more if it is starting to taxi.

AIP-AIR 1.7 contains an elaborate table of distances and wind velocities behind propellers, depending whether the airplane is leaving a parking area, taxiing, or at take-off. All you need to know for the PSTAR is 45 kts --> 60'. It's the smallest distance given in the answer choices.  I have seen a heavy baggage cart blown right off the dock into the water by a twin otter turning around to taxi out.

11.13, 11.14 and 11.15 See VDF steers, above.

11.16 SIRO stands for Simultaneous Intersecting Runway Operations. Landing aircraft can be told to land on one runway and hold short of (stop before reaching) a crossing one.

11.17 Even if you have already accepted the clearance, if you can no longer hold short, inform ATC immediately. If you think the aircraft you were holding short for is no longer a problem, and you are just sitting there waiting, you can call ATC and just say, you are "holding short" of the particular runway. They will either clear you across or give you some information about why you are still holding.

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This page written 8 October 2002 by Robyn Stewart. Last revised 5 September 2004.

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