Aircraft Enhancement

Aircraft Enhancement occurs on 2 meters (144mHz) within the VHF band and in my experience has a close group of followers.
The distances expected with this mode of propagation are around 200 to 600Km and are quite predictable allowing communication from a few seconds to a few minutes.

Equipment Requirements for Aircraft Enhancement

Reasonably modest equipment will get you by for Aircraft Enhancement and the only real requirements are a ssb 2 meter transceiver and a horozontaly polarized antenna.
The degree of success will depend on the sensitivity of the reciever, the feed line quality and antenna gain and directivty.

The Rig

Power output from the transmitter of around 50 watts or more is recomended but a 10 watt station can do very well.
The Transciever must be an SSB 2 meter rig with as much reciever sensitivity that can be mustered up. Noise Blankers and DSP filters are also handy features. Also if no mast head preamp is used a preamp in or before the rig is very handy indeed. Good examples of Transievers for AE would be the IC-706 or FT-847.

Feed Line

Feed line should be as efficient as possible and hard line should be used. That said RG213 or equivilent will do the job for runs under 10 metres or so.

Antenna

Really I would not consider using any thing less than a 7 element yagi with sensible spacings. DL6WU designs are quite good and give good tolerances for a reasonably predictable performance. Designing the antenna at the intended operating frequency also leads to predictable performance.
At the other end of the spectrum there is no limit as to the size of the array that could be used. Just be aware that more gain generally makes for more directivity and bigger arrays.

Where do I find Aircraft Enhancement on 2M?

On the East Coast of Australia AE operators use the secondary SSB call Channel which is 144.200mHz.
USB is the mode mostly used but you will also hear CW in there as well.
There is a fairly organized schedule to it all and the action usually starts every morning from 7:00AM local time with more activity on week ends.
There is also a 2 meter DX net between VK2 and VK4 every tuesday night starting at 18:50 hours local time.

Operating Procedures
HF operators may find some of the operating behaviours on 2m SSB a bit strange to say the least, some may evewn feel that operator are bening rude or inconciderate but this can be clarified quite easily.
On 144mHz propagation paths do not often hang around for hours, particularly AE. There is some what of a gentlemens agreement that if you hear it you can call it. That said once a contact is established others must wait there turn. Also conditions can be quite selective, so you may be the only station hearing the DX at that time.
QSOs are kept very short and mostly not more than call signs, first names, grid square and signal report are given and conformations of all recieved are involved in the QSO, not forgetting 73s of course.

Maybe the strangest behaviour of all is the letter K that is often whistled at the end of a transmittion when calling CQ or signals become weak.
Some use automatic keyers to send the K in CW and some just whistle it, either way its just there to let other stations know when your transmition is over ( particularly as conditions deteriate).

As a last note, as with most call frequencies chatting on 144.100 or 144.200 is frowned upon and changing to another frequency is recomended if any thing more than a few very short overs are planned.

Good Luck. Enjoy!