The phraseology issue is adequately dealt with in the report:
In this particular event the Shannon Low Level Data Assistant relayed the clearance as “[...] Flight Level Two Zero Zero[...]”, and that is what the EIKY Tower Controller read back. Subsequently, the EIKY Tower Controller gave the clearance as “[...] Flight Level Two Hundred[...]” and that is what the Flight Crew read back. When queried by Shannon Low Level Control as to their passing altitude the Flight Crew Reported “Ah we are level Flight Level Two Zero Zero.” When queried again, the Flight Crew reported “We were cleared only to Flight Level Two Zero Zero”. The fact that these first two replies are both in the single digit form i.e. “Two Zero Zero” leads the Investigation to believe that the Flight Crew had correctly interpreted their initial clearance to “[...] Flight Level Two Hundred[...]”.
Consequently, the Investigation does not believe that non-standard phraseology played a role in the Flight Crew's misinterpretation of their cleared Flight Level.
Evidence that the Flight Crew were confused can be found from the Pilot-in-Command's statement which says “we informed the controller that we were unsure”; however, there is no recording that this actually happened.
In fact, it appears that it was only following three direct inquiries in quick succession from Shannon Low Level Control that the crew identified that they were confused about their cleared level. When the Shannon Low Level Control enquired for a third time the Flight Crew reported “and we confirm that we are cleared up to Flight Level Zero Two Zero... Two Thousand feet”. This was a change from the Flight Crew’s two initial reports that they were level at “Flight Level Two Zero Zero” and probably reflects a realisation of their behalf that they had correctly heard and recorded “Flight Level Two Hundred/Flight Level Two Zero Zero”, but that they had misinterpreted its meaning. This is supported by the fact that the Flight Crew did not at any stage request a clarification of their cleared Flight Level which, if they were confused or concerned, would be good airmanship and is the practice advocated by Eurocontrol.
The Investigation also notes that the Flight Crew’s transmissions featured several instances of single digits being read back in group form e.g. “Two Zero” read back as “Twenty”,“Three Zero” as “Thirty”, “Four Zero” as “Forty”, “Five Zero” as “Fifty”, “One Two Four decimal Seven” as “Twenty Four decimal Seven”. It therefore appears that, although it is not ICAO standard phraseology, the Flight Crew were comfortable working with grouped digits and should not have had a difficulty interpreting “Flight Level Two Hundred".
The whole matter really begins and ends with these extracts direct from the report:
At 14.36:28 hrs, the Flight Crew called Shannon Low Level Control saying “Shanwick good afternoon Hawker November One Three One Zero Hotel Flight Level Two Zero Zero direct Vener”. Shannon acknowledged “November One Three One Zero Hotel Shannon control confirm squawk and passing altitude”. At 14.36:40hrs the Flight Crew replied “Ah we are level Flight Level Two Zero Zero and squawking Six ThreeZero Four”. Shannon Low Level Control then said “November OneThree OneZero Hotel Shannon radar contact and just confirm your passing altitude”. At 14.36:51 hrs the Flight Crew replied “We were cleared only to Flight Level Two Zero Zero”. Shannon Low Level Control persisted “Okay sir that’s copied but your passing altitude...your current altitude”. At 14.36:59 hrs the Flight Crew replied “And we confirm that we are cleared up to Flight Level Zero Two Zero... Two Thousand feet”.
And:
The Planning Controller said that when the Tactical Controller cleared N1310H up to Flight Level Three Hundred the introduction of the new Flight Level seemed to snap the Flight Crew out of the Flight Level Two Hundred/Flight Level Zero Two Zero cycle.
Conclusions:
1. Cause of incident: Unanimous Flight Deck Brain Fart
2. Good pick-up by ATC