Investigators asserted that the performances by the traffic controllers were proper and that the misunderstandings that were made were reasonable. None of the controllers involved considered the word "priority" or the assertions by the flight crew that they were running out of fuel to be indicative of an emergency. The report provided various examples of the flight crew failing to convey the danger of their situation, even moments before the engines flamed out. Although the investigators felt that the communications from the ATC personnel were "proper," the NTSB voiced concern over the controllers "not" placing significance on the word "priority." At a public hearing, it was revealed by an unrelated pilot that the emphasis on the word "priority" by the Avianca crew might have come from training and bulletins from Boeing that used the word in relation to fuel emergencies. Avianca also used the word "priority" in its publications on low-fuel status procedures. ATC controllers testified that "Mayday", "pan-pan", and "emergency" were the three phrases that they would respond to immediately. The report also stated that "priority" was defined in the ATC Handbook as "precedence, established by order of urgency or importance." As a result of this linguistic confusion, the NTSB recommended that the FAA work with the International Civil Aviation Organization (ICAO) to develop a standard glossary of clearly defined terms as well as notify foreign carriers that they must be knowledgeable of ATC rules and procedures.