The Art of Unreasonable Expectations

Being out of touch with the world for an entire week is difficult for an information junky like me. There are a number of topics to discuss, a number of interesting events that occurred, but in the end I can only cover so much from the time away. One of the more interesting articles I came across was the is the June 2007 issue of Defense Technology International that has a decent article on the British CVF.

However, one of the comments that struck me as somewhat odd, or overtly rediculous, was the expectation that a single CVF can provide 360 sorties per day, with each aircraft making around 10 sorties in a 24 hour period for 5 straight days. No matter how you cut it, this is wishful thinking of an incredibly rediculous kind.

Why is this rediculous? Because, in the real world those numbers don't reflect reality. RAND produced a sortie rate model several years ago that still holds true today. Their formula is easy to follow, and can be used to educate an aviation novice in military affairs 'how things really work.'

Sortie Rate = 24 hours / Flight Time +Turnaround Time + Maintenance Time

Last year, in an article highlighting the retirement of the F-14, and the differences between it and the F-18, Navy NewsStand reported on the maintenance hours of the F-18E/F Super Hornet to be somewhere between 5 and 10 hours. We will assume 5 hours for this exercise.

The RAND report covers the math regarding the Turnaround Time. The following table from the report shows the figures for USAF Turnaround Time for F-15s and F-16s shows 180 minutes, or roughly 3 hours for Turnaround Time, which doesn't include maintenance hours. While there is no good public data for the F-18, assuming anything more than a 33% improvement over these times is being completely unrealistic, but would be 2 hours Turnaround Time.


Flight Time is calculated by the distance the aircraft carrier is from the target. This is where Navy's tend to fudge the numbers some, in fact the US Navy likes to use the figure 250 nautical miles from target. I prefer the more realistic 500 nautical miles to target with an average flight speed of 500 knots, because many SH pilots have testified this figure to be more realistic. This means 1000 nautical miles round trip at an average of 500 knots, or roughly 1.68 hours. Given these numbers, we can now compute the sortie rate for the existing F-18E/F.

Sortie Rate = 24 hours / Flight Time +Turnaround Time + Maintenance Time
Sortie Rate = 24 hours / 1.68 hours +2 hours + 5 Hours
Sortie Rate = 24 hours / 8.68 hours
Sortie Rate = 2.76
46 F-18s x 2.76 = ~127 sorties per day

It has become vogue to claim that number of aimpoints (bombs) per aircraft means sorties, but it actually doesn't. It is absolutely true that each bomb can be independently targeted, but I think it is a bit dishonest to say that each bomb is a unique sortie. The F-18E/F would potentially be able to carry 6 aimpoints (bombs) in addition to other weapons per sortie, while the older F-18C/D can carry 4, so in this case each plane is able of a certain number of targets. Assuming that all 3 Navy squadrons (2 are SH squadrons) are 12 planes and the USMC squadron is 10 planes, the 46 planes would represent 232 aimpoints per sortie. This means a typical US Carrier with 4 F-18 strike squadrons is able to support 640 aimpoints per 24 hour period.

The article is assuming the Joint Strike Fighter V/STOL version, which is considerably more complicated than the simplistic F-18 design, will be able to achieve a sortie rate of 360 per day, or roughly 38% more efficient than the current US Navy carrier that has more planes of a less complicated design.

Believe what you want, but it is rediculous to assume a VSTOL Joint Strike Fighter is going to somehow achieve a 360 sortie rate per day capability for 5 straight days on the CVF. The numbers simply don't add up. Assuming the VSTOL Joint Strike Fighter is equal to the F-18E/F in sortie rate, or roughly 2.76, the CVF should average around 100 sorties a day, or roughly 400 aimpoints per day, which is still a substantial upgrade over existing carrier aviation capability for the Royal Navy, but not the unreasonable figures being promoted by some.