Technical Writing in the Aerospace Industry

by David Tinsley

This article covers my experience in technical writing for the aerospace industry, which spans over ten years and two continents. My specific specialty is avionics, which essentially means any system on an aircraft that can be considered electronic, from the inertial navigation system to the audio controls in your seat, to the electronic countermeasures on a military fighter and all points in between. As you can imagine, a background in the industry is a prerequisite and I have never met an avionics technical writer who was not an engineer in a previous life. So it was with me. Over 25 years stuck up the bowels of aircraft gave me a good grounding for user expectations in avionics documentation!

Typical Range of Manuals

Avionics technical writing can be split into two broad disciplines; military and civil. These may be further split into on-aircraft and component (black box) level shop maintenance. The range of manuals required for a typical project may include the following:

• Theory of operation (how does it work and what does it do?)
• Installation (how do I fit this in the aircraft?)
• Operation (how do I operate it?)
• Repair (how do I fix it?)
• Testing (how do I know I have fixed it?)
• Illustrated Parts Catalogue (IPC) (what parts can I get to fix it?)
• Modification leaflets (how do I upgrade the equipment?)
• Destruction (how do I destroy it?) (This is an interesting one. It covers the destruction of classified or essential components or systems. It is written to detail what parts of an aircraft should be destroyed to make it unfit to fly or to destroy classified equipment. It is designed to be used if an aircraft may fall into enemy hands, in wartime if a unit is about to be overrun.)

The Process

I write the manuals following the normal procedure of interviewing subject matter experts, poring over drawings and design specifications and, if I am lucky, sitting on the flight deck and checking the procedures. I say lucky, because, as everywhere, production cannot stop to let some lowly writer get his grubby paws on the aircraft. This is where previous experience in the industry counts a lot. If you are a professional aircraft engineer, then you are more likely to be allowed to run through your procedures.

There is little difference in the style or depth of writing between military or civil aircraft. The audience is essentially the same: aircraft maintenance engineers. Most avionic systems are the same on both types of aircraft, the main difference being the weapon control systems and electronic countermeasures on military aircraft, which aren't normally included on your average aircraft taking you on holiday to Mexico!

One major difference the writer has to consider between the military and civil users is the customer. In the civil world, buying an aircraft is much like buying your new Ford. "Here you are Sir, the keys to your new Bombardier CRJ200. We have filled the tank and here is the manual. Be sure to read it." However, it is not the same for the military customer. The manuals tend to be part of the deliverable and go through very thorough vetting for completeness, adherence to styles and so on. There are often two customers to please: the aircraft manufacturer; and the end user. So, the manual you have written for the Tornado avionic system will go to British Aerospace and then on to the UK Ministry of Defence publications procurement agency. Pleasing that bunch can be challenging to say the least!

Specifications

The aerospace world is awash in documentation specifications, but at least they do achieve consistency. They cover the expected items such as page layout, font, paper weight, binding, electronic delivery. Some of the more common specifications are as follows:

• ATA 100 -- Air Transport Association manual styles
• ATA 2100 -- Air Transport Association SGML DTD
• AECMA 1000D -- The European equivalent to ATA2100
• Defence Standard 0060 --The UK MOD specification
• Mil Specs -- There are many US military specs pertaining to documentation

Luckily I only have to write to one specification on each project, but moving on to new projects can be confusing.

Simplified English

The manuals I wrote for the Bombardier aircraft were written in simplified English (SE). SE is a method of writing designed for users whose first language may not be English. It is designed to remove ambiguity and achieve clarity. SE was first introduced in Europe by Airbus Industries and has its own dictionary and style guide. For example, consider the following phrase "Tighten the filter hand tight" Now I am a hulk with hands like a backhoe. My hand tight may well strip the threads. SE does not allow such subjective instructions. It would be written "Turn the filter until the sealing ring touches the housing and turn the filter a further half turn" One drawback of SE is that if English is your first language then reading SE makes you shudder in its composition! SE could be the subject of an article in itself. More information can be found http://www.userlab.com/SE.html

SGML

The aerospace industry is one of the main users of the SGML standard. All the major manufacturers use it. At Bombardier, we used Adept Editor for inputting text. The drawback was that we did not get a WYSIWYG view and only saw the final output when the manual was published. The advantage was that we could forget about page layout etc and concentrate on the content. Personally I did not like working in SGML; I missed having control over the look and feel of the document. Again the subject of SGML is an article in itself.

And Finally...

Have I enjoyed my writing career to date? You bet! To know that aircraft are being signed off as safe for flight after following maintenance procedures that you have written provides a great sense of satisfaction. The range of systems I have documented have been numerous and the advances being made in avionics means that there will always be new technology to learn. I hope this article has given some insight into an overlooked industry that employs many technical writers.

This article has only touched on the complexities of documentation in the aerospace industry. Please feel free to contact me at mas43@sentex.net if you would like any more information on my experiences.

David Tinsley just recently left the aerospace industry to become the Supervisor, Technical Communications at Northern Digital Inc. in Waterloo.