Maybe we can start a new meme. Whenever someone talks about their super-duper awesome social ajaxy photo-sharing app, we can snarkily respond "well, it isn't exactly rocket programming..." :)
Avionics software development is primarily concerned with software that is designed and developed to operate in an embedded system [1]. There is also a focus on real-time performance [2] with regard to the software's operation and integration in such an environment.
The target language may be C, C++ or assembly language, although other languages are used.
Depending on the application, an on-board front-end may or may not be utilized. For example, an unmanned rocket would not contain a front-end; rather, operating parameters would be monitored remotely.
On the other hand, a modern, manned aircraft or spacecraft instrument panel would provide electronic displays and controls necessary for communicating system status to the pilot(s), as well as for accepting input from the pilot(s) for operation and flight.
The software process that develops the applications are very different. An avionics system must be able to operate autonomously, must have robust fault detection and tolerance, and must interact directly with many hardware components.
Web apps tend to layer on top of other systems and can reuse a lot of code. When I worked on avionics software we had to develop everything, from the hardware drivers for memory modules to the drivers for the display and all of the controlling systems for each of them. A high-performance web app just needs to perform well enough - at some point you can add more hardware. In an avionics platform you have specific weight, cooling, and power requirements that limit your total hardware capability. They are really very different.
A good analogy would be the difference between being a brief writer for a law firm and being a fiction author - you have "writing" in common (hopefully "good writing" at that) but the intricacies of each domain make it appreciably different.
Web application programming relies on a plethora of "soft" technologies (xhtml/html5, css, javascript, sql/nosql, php/python/ruby/perl, frameworks for all of it, a lot of 3rd part libraries outside of the frameworks, etc...) - embedded programming is much more low level in comparison and comes with many different kinds of problems.
Maybe we can start a new meme. Whenever someone talks about their super-duper awesome social ajaxy photo-sharing app, we can snarkily respond "well, it isn't exactly rocket programming..." :)