Ask the Captain: What do the in-flight chimes mean?

Question: During a flight, I've noticed that there are "dings" when announcements are being made. I once heard a rumor that two dings is something more common (such as fasten seatbelts due to rough weather ahead), while 3 and 4 "dings" are for much more serious issues during the flight. Is this true?

-- submitted by reader Dean Turner, Vancouver, Wash.

Answer: Different airlines use the chimes differently. Here are some uses I've witnessed in my career:

• A single chime could be to the flight attendants to advise them of pending choppy air, perhaps serious enough that they should be seated. Another possibility would be, "when you have time, could we please have a coffee?"
• Two chimes are often used to indicate the aircraft is approaching 10,000 feet in altitude.
• A 3+ chime could be to tell the flight attendants to be seated NOW due to reports of turbulence that were just received by the pilots.

Cabin crew can also use the chimes to communicate with the flight deck. A single chime could be, "would you like coffee?"

A 3+ chime to the flight deck could be, "we have a passenger with a medical problem that could require a diversion."

I would not automatically draw the conclusion that more chimes indicate a serious problem.

Q: I was on a flight over the weekend and the temperature of the cabin had to be around sixty degrees or less the whole flight. Who determines the cabin temperature? Is it pre-set by the aircraft, airline, flight attendants or captain?

-- David Rabe, Sarasota, Fla.

A: The pilots have control of the temperature of the cabin. If you are uncomfortable, let a flight attendant know and they can advise the pilots to adjust it.

Q: When a passenger says "nice flight or smooth landing" to the pilot or co-pilot, does this have any meaning to them?

-- Andrine, Brunswick, Maine

A: We always appreciate comments from passengers. Yes, it means a lot to hear that you enjoyed the flight.

John Cox is a retired airline captain with U.S. Airways and runs his own aviation safety consulting company, Safety Operating Systems.