Air travel is especially safe compared to other means of travel because among other things it´s subject to numerous surveillance and security systems. We´ve already examined some of them in this blog, such as how a transponder works, flight controls, communication with the control tower, and much more. Today we´re going to talk about checklists – what are they and what do they accomplish?
The checklist is basically a tool designed specifically for crews whose objective is to reduce human error as much as possible. The operation of each aircraft relies, of course, on the people who crew it, but also on standardised devices and protocols, so that potential human error or forgetfulness don´t have unfortunate consequences.
So the checklist helps reconcile the two, aimed at exhaustively ensuring that each necessary task has been carried out, and it´s set forth by the United-Nations-affiliated International Civil Aviation Organization.
First of all, we need to distinguish two types of lists: those of normal procedures and those of abnormal and emergency procedures.
In the former (there are several, as we´ll see below), the main objective is to help the crew configure and check all the aircraft´s systems. It does this by facilitating the coordination of tasks in a logical and proportional way, allowing mutual observation and exchange of information by all crew members and providing sequences to verify the pilot station panels and to satisfy all operational requirements, both internal and external.
With the latter, information must be provided to resolve potential difficulties or emergency situations related to an aircraft failure. It also aims to ensure that standards are met in the event of a hypothetical overload of tasks. The abnormal and emergency procedures checklists will help each member assume a clea role and act as a guide to make decisions, executing actions in the appropriate order.
Finally, a checklist can come in physical or digital form, and each aircraft has its own.
What´s on a Typical Checklist
The Normal Checklist
- Pre-flight inspection list (both exterior and interior).
- Before starting engines.
- During engine ignition.
- Before taxiing.
- During taxiing.
- Before takeoff.
- After takeoff.
- On ascent.
- At cruising altitude.
- Before descent.
- Before landing.
- After landing.
- Before switching off engines.
- Assurance checklist.
The Abnormal Conditions/Emergency Checklist
This informs the crew how to proceed both in unusual situations (turbulence, ice on the runway, etc.) and in those that are due to a failure in the aircraft (in an engine, for example, or warning lights). In this case, the most common thing is to use the QRH (quick reference handbook), a condensed version of the aircraft flight manual. It is segmented and divided with tabs so that crew members can quickly access the procedure they need to see. There are usually two copies of QRH in the cockpit, so that the two pilots can consult it simultaneously if
necessay.
Additional Checklist Considerations
These lists must meet a series of common-sense requirements:
First of all, a logical order. Each list of each procedure must have one order and not another within the elements which are verified, since there are systems that depend on others.
The answers to each item checked should be as specific as possible, so as not to leave room for ambiguity.
They have to correspond to specific phases of the flight, and be just right – not too few, not too many. There are automatic systems that verify parts of the protocol, which means that some elements of them can be left out for human attention.
The list has to be intelligible and verifiable at a glance. To do this, the choice of font is essential: one must be chosen that is easy to read – neither too condensed nor too embellished – and legible even at times when visibility is poor.
Color codes can be used, but with common sense: in green, the normal checklists; in yellow, those that indicate the malfunction of some system; in red, those for verification of emergency procedures. However, it is highly recommended that color is not the only element that distinguishes them.