There are a number of Amateur Radio operators (aka. "hams"), who believe that ALE is a solution in search of a problem. It is for those, that the following is written:
The automatic link establishment protocol (aka. "ALE") used for high frequency (HF) radios, is a vendor-independent protocol, which does exactly as it name implies. It automates the establishment of an HF link between two stations. Technical details are sufficiently documented and freely available on the Internet.
Experienced HF radio operators are fairly good at estimating which frequency (band) will likely result in good two-way reception between two stations at a fixed distance from one another at any given time of day.
If however, there are more than two stations who want to be able to communicate with each other without prearranging a schedule and who are at various distances from each other (e.g. 20miles, 200miles, 1000miles, 2000miles, 4000miles), then experience alone is not the solution. How is the radio operator to know who is wanting to contact him right now and that with 24/7 coverage? Since the other stations are at varying distances from him, which frequency should he be listing to?
One could of course buy a dedicated transceiver for every frequency and band that one would need to cover, but the cost for such a setup is prohibitive and arguably impossible to accomplish for mobile and portable stations.
This is where ALE comes in and thus is indeed a solution which solves a real world problem and does so more efficiently (less bandwidth and less time consuming) than any "experienced" radio operator could.
73 de Marcus NX5MK