Ask the Captain: How does air traffic control deal with foreign languages?

— -- Question: On international flights, how do pilots and air traffic controllers accommodate the language barrier? Are flight crews on Air France flights, for example, required to speak English once entering U.S. air space? Are the ATC's bilingual? What about a Russian pilot flying into Brazil?

—submitted by reader KMorley

Answer: The international language of aviation is English. In most places, the pilots and air traffic controllers have demonstrated the ability to speak and understand English up to a level specified by the International Civil Aviation Organization (ICAO). Some of the accents can be very challenging. By using ICAO standard phraseology and speaking very distinctly, the necessary information is transferred.

Your question about a Russian pilot flying into Brazil is one I had not considered. Both countries are part of ICAO, making both of them demonstrate English language ability. I believe they would use English.

Q: I was listening to Channel 9 on a United flight this week and our United call-sign was followed by "kilo." So we were United 976 Kilo. What does the Kilo after the call-sign mean? And how about Tango - I've heard that, too. It makes sense for aircraft identified by their registration numbers, and I know about the "heavy" and "lifeguard" designations, but I can't find information about why Kilo or Tango are added to a commercial flight call-sign.

— fuzz4000

A: Great question. To ensure that my answer was correct, I checked with a colleague at United.

Because airline flight numbers continue through hubs to other destinations, occasionally there can be two different flight plans on file at the same time. An example would be if Flight 123 inbound to the hub was delayed, the outbound segment flown by a different airplane could be airborne at the same time. To prevent confusion and the potential conflict within the ATC computer, a letter suffix is added to one of the flights. One flight remains Flight 123 the other is Flight 123K or 123T. The phonetic alphabet used in aviation uses the word kilo for the letter K and tango for the letter T.

On your flight, United 976 Kilo was a flight with the potential for another segment to be flown near the same time as you were airborne. Kilo was added to your flight number to avoid any problems within the ATC system.

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