If Pratt & Whitney and CFM had not brought out the new engines, would all those customers who ordered the A320 neo have placed orders for regular, CFM56 or V2500-powered A320s? Probably not to the same extent. We will never actually know the answer.

There would have been some new orders but judging from what has happened to the backlog positions of all other programs, any gain since the start of 2011 might have been relatively small. In the first five months of this year the backlog slowly declined. By the end of May it had dropped by 167 aircraft and while something might have happened in June, at the Paris air show, nobody seriously thought that there would be a massive backlog increase. Something modest, perhaps, but the industry was not particularly interested in the backlog at the time. It was healthy and it represented work in hand for several years to come. Even if it slowly declined for the rest of the year, in overall terms, it would have been no big deal.

The new engine option changed all that. Since the start of June the large commercial jet backlog has increased by over 1,300 aircraft, or 18%. This means that the backlog at the end of November was 1,151 aircraft greater than at the start of the year. This is almost entirely due to the new engines. The A320 neo Family backlog is currently 35 times greater than it was at the start of this year. But the gain of every other aircraft program combined has been less than two percent. All these other aircraft programs had a combined backlog of 7,380 aircraft at the end of November, or 129 aircraft more than at the start of the year.

The Airbus backlog is currently 901 aircraft larger than at the start of the year. Boeing's backlog is 92 aircraft larger. The other three manufacturers all have larger backlogs now than they had at the start of the year but we are not talking very large numbers here.

The big mistake is to think that backlog gain this year is across the board. It isn't.

Airbus' A318, A319, A340, A350 and A380 programs all now have smaller backlogs and only the A320, A321 and A330 programs have larger backlogs. But one has to be careful here; the regular A320 backlog has dropped by 242 aircraft. The overall A320 backlog, including the neo, is up.

Boeing is in much the same position; the 737 backlog is currently six aircraft larger than at the start of the year and the 777 backlog is up 127 aircraft. However, the 747-8, 767 and 787 programs all now have smaller backlogs than at the start of the year.

Demand for the new engine option has pushed the single-aisle backlog up by nearly 1,100 aircraft this year and it currently stands at close to 6,000 aircraft which is pretty much how large the entire large commercial jet backlog was roughly four years ago. More to the point though, the Airbus share of the single-aisle backlog is now 56%. At the start of the year the Airbus held less than half the single-aisle backlog. Six percentage points may not seem very much but the Airbus single-aisle backlog is now 930 aircraft larger than it was at the beginning of the year.

Recent orders for the 777 have helped to push Boeing's widebody backlog up by 86 aircraft, to a total of 1,343. Of all widebody programs, only the A330 and the 777 currently have larger backlogs than at the start of the year and while Boeing's widebody figure is up, the Airbus widebody total is currently 29 aircraft less than it was at the start of the year. Boeing's 787 program has had the largest backlog decline of all widebody programs and is currently down 28 aircraft on the figure at the start of the year. The A350 is down 16 and the A380 is down 13 aircraft. The A340-500 backlog is now down to two aircraft following the Kingfisher cancellation in November.

Year-end orders will boost both the large commercial jet and the large civil jet engine backlog figures in overall terms but the real gains will be due to just a few programs and will certainly not be across the board.

If you get "Aircraft Engines" every month, you will have the very latest information on all the engine programs as well as the commercial aircraft programs.