Avoiding Ambiguity in Communication

At a late stage of flying training (embarrassingly late from my perspective) I was picked up by my instructor for requesting departure clearance from Air Traffic Control (ATC). During our taxi to the holding point, I made the request and ATC read our clearance to me as usual. It was only later when my instructor went through the debrief, that the importance of clear communication was highlighted. We spoke about the confusion that could have occurred between my clearance request and a request for departure. A slight difference in wording, with two very different intentions.

Aviation safety is underpinned by clear communication. It is essential that every party, whether it’s ATC, the pilots, or ground handlers, knows what is happening, when it’s happening. Ambiguity causes confusion, confusion causes hesitation, and hesitation can cause an accident. I heed the warning from my instructor, and now without fail ensure that I am clear with what I am requesting! Fortunately, there are documents that stipulate the correct voice procedures for aviation, so everyone operates from a common framework.

For those in the UK, Ireland, US and Canada, it is (relatively) easy; the aviation world communicates in English. This dates back to December 1944 when the Chicago Convention was signed. Officially titled the Convention on International Civil Aviation, the agreement signed in Chicago was between 52 states, agreeing how aviation would operate globally. One of those conditions was the use of English as the primary language, to help avoid confusion over radios. However, for most other nations who operate in international airspace under ICAO (International Civil Aviation Organisation), English isn’t always their first language. This is just one of many communication barriers that exist within aviation, which subsequently contributes towards incident occurrence.

Ambiguity in communication can prove to be fatal in aviation, as we saw in Tenerife back in 1977. Two Boeing 747s collided on the runway at Los Rodeos Airport in Tenerife, leading to the loss of 583 lives – the greatest loss in a single incident aviation history! Due to a bomb explosion at Las Palmas, aircraft had been diverting to Los Rodeos all day and the airport was congested. Many aircraft were parking on the taxiway, which meant departing and arriving traffic had to taxi along the runway. To make matters worse, the airport was in dense fog, with visibility reported as less than 300m! KLM Flight 4805 misunderstood their instructions from ATC, thinking they had been given clearance to take-off. As they progressed along the runway, they collided with Pan Am Flight 1736 who were still on the runway. The full report is a harrowing read and goes into more detail about the events of the day, but in summary, the primary cause of this accident was the KLM captain’s assumption (through various factors) that he had been given that departure clearance.

As mentioned earlier, to assist in avoiding this ambiguity there are a series of standardisation documents. One of these, CAP 413, is the CAA’s Radiotelephony Manual. My departure clearance request issue is even in here – I should have just requested clearance, as later you stipulate ready for departure. For a manual, it’s very easy to read and gives clear examples of how pilots and ATC should communicate. In most situations communication is pretty much scripted, which is a massive help to avoiding ambiguity, as both parties are expecting a series of standardised responses.

Having flown around the world and communicated with various nations’ ATC agencies, the importance of clear communication is crystal clear. Accents can make understanding even the scripted CAP 413 conversations difficult at times, however asking for instructions to be repeated is never a bad thing! It’s better to be 100% sure of what is being said, even if it means asking for it to be spelt out phonetically. The NATO phonetic alphabet has helped many times when trying to find obscure GPS waypoints. Despite these tools being available to help avoid ambiguity in communication, there will always be issues with accents, broken radio transmissions and human error which will inevitably cause some confusion!

Although this has been a look at the aviation domain, communication is important in every aspect of life. Whether it's work, relationships or hobbies, the way we communicate with each other determines how successful we are in our endeavours. Sometimes avoiding ambiguity is as simple as just saying what we mean (however difficult that may be), but we could always be better at the way we communicate our ideas and points of view!