Question: An airliner is cruising along at FL 350. The captain announces to the passengers that the outside temperature is minus 40 degrees Fahrenheit. In order to keep the cabin nice and comfortable, what system is essential?
- In almost all airliners, surplus power from the engines is used to power generators that supply electrical energy to generate heat.
- Actually, due to the friction generated from flying over 0.5 Mach, airliners actually need air conditioners to cool the air before it enters the cabin.
- Choice A is close, but it is simply excess heat from the engines which passes through radiators with vanes that are used to warm the incoming air.
- Simply pressurizing the cabin generates heat, and in fact, temperatures could conceivably climb to Death Valley digits if the air were not also refrigerated after being compressed.
Answer: D. Think about the ideal gas law PV = nRT (where n is the number of moles, R is the gas constant, and P, V, and T are pressure, temperature, and volume respectively). If volume is held constant, then when you raise the pressure, the temperature will rise accordingly. If heat were not extracted from the compressed air, temperatures could reach as high as 130 degrees F.
Subject: Bogeys, Twelve O’clock? There’s Nobody There!
Question: What is the squawk code 5200?
- This is actually used for the F-117A and the B-2 in training maneuvers.
- This is the emergency code used by the US Air Force for emergencies. (The Army uses 5100, the Navy 5300, the Marines use 5400, and the Coast Guard, 5500.)
- If you ever hear someone mention a squawk code of 5200, bring your radio into the shop, because you’re picking up maritime chatter. This code (and those in the 5200 range) are used by ships at sea.
- This code is used in the agricultural application industry much like 1200 is used in general aviation.
Answer: C. Transponders are not just for airplanes! Ships at sea are often assigned codes in the range of 5200.
Subject: Uh Oh! What’s THAT Mean?
Question: Nearing the end of your return flight home, as you’re descending to enter the traffic pattern at your home airport, in addition to some nearby red and green lights, you happen to notice a blue flashing light above you. What does this mean?
- You are in serious trouble. In addition to a flashing or occulting red beacon at the top of tall towers, a flashing blue light is used to indicate the point where guy wires are attached.
- It’s a blimp. Just don’t climb.
- Although it is done fairly rarely, whenever parachute jumps are made at night, the jump airplane must display this, in addition to other position and navigation lights.
- Air-to-air refueling is being performed.
Answer: D. A blue light means that air-to-air refueling is taking place. (And if your radio could transmit on 266.500 MHz, you might try asking them yourself.) Actually there are various lighting assemblies used on the aerial refueling pod (such as red, green, and amber), as well as on the tanker aircraft itself.