Can aeroplanes flying overhead disrupt mobile phone signal?

if it is a large enough AC that is between you and the cell site there MAY be a momentary disruption in an analogue phone BUT using a digital phone you shouldn't notice it but you would see it with the proper test equipment. The frequencies involved as other posters have said are line of sight from the tower to you and anything large enough will block the signal but the planes are flying at a around 100 mph and you wouldn't notice the disruption by ear.

Not knowing where you live I suspect that you are at the edge of several cell sites OR down in a low area where the signal is marginal. If you live near a busy airport it would seem like they are causing the problem

I haven't researched the subject for over 15 years, but I thought phone stuff was on 2.4 GHZ. There is nothing on an aircraft in that frequency range. Or at least there wasn't 15 years ago. As the "radio operator" noted, you are probably getting some kind of reflected signal to cause your interference. The FCC used to check these anomalies for free. Call them!

If you have a satellite phone instead of cell phone, the aircraft could block your signal.

Mobile phones communicate with cellphone towers using radio. Typically at frequencies near 900 MHz. At these frequencies signals can be directional and are often described as line of sight. Thats not as straight as a torchlight would be, but considerably more directional than at other frequencies. Radio signals can be reflected or refracted by obstructions along the path - metallic aircraft being good reflectors. It is likely that part of the radio signal is being reflected by or "bouncing" off he aircraft. This could cause the mobile to communicate with a different local cell tower. Additionally it is likely that part of your signal is taking a different path (not bouncing). These two different signals are then likely to cause interference with each other (see wave interference). If you want to improve signals you can either improve radio power (more powerful mobile or different frequency) or improve path (different operator using different cell tower, or place yourself between the phone and the aircraft - you might get a more direct path).

Clearly your experience has shown that the plane itself or the radio emmisions from them interfere with the mobile phone signal - cannot be more scientific than that

Aircraft do contain radio transmitters: a transponder, to respond to airport radar, and for voice communications. Interference with cell communications is certainly possible.