As part of an airliner’s certification process, the manufacturers take into account what the likelihood of non-normal operation of that aircraft’s various components and systems would be. The process is rigorous and scientific. Manufacturing standards, testing, in-service evidence and conventional wisdom all play a part as well. If there is a possibility or probability of a non-normal operation of a component or system triggering an event that requires attention from the flight crew, however small or insignificant it might appear to be, a procedure for how the flight crew should deal with that non-normal event will be written and included in the pilot’s Quick Reference Handbook (QRH).
Both pilots have a Quick Reference Handbook
Both the Captain and the Co-Pilot have their own QRH’s. They are located in pouches on each side of the centre pedestal of the cockpit. The books are robust and well printed and their indexing is extremely good. They have a general alphabetical index and then there is also an easy means of accessing any one of the fifteen or so different aircraft systems. A sub-index within a particular system’s chapter then leads the pilots directly to the malfunction that actually exists.
A checklist is written for every possible conceivable non-normal situation.
Most jet airliners have QRH’s that have as many as 250 listed “non-normals” that could occur. Some of these could be very simple and the checklist could have as little as two written lines that will suffice to restore the system to normal. On the other hand there are also malfunctions that are very serious in nature and that might even need to be treated as emergencies. The point is that for virtually every technical problem that could manifest, there is a laid down procedure that must be followed. This will also prevent any “knock on” effects down the line because of the failure of a crew to take further implications of the failure into consideration.
One of the twin jet airliners I am familiar with has 255 written procedures in its QRH. Of these, 17 are regarded as being of emergency status. The associated procedures for these require immediate action from the pilots. Such emergencies would, for example, be related to engine failures, fires, smoke or fumes anywhere in the aircraft, or the loss of pressurization, to name only a very few. Pilots are obliged to commit these procedures to memory and to be able to execute whatever actions that are specified by recall. In the QRH Index, these particular checklists are all printed in a bold font.
The checklist will state very clearly when a landing at the nearest suitable airport must be planned.
Going one step further, still in the same aircraft’s QRH, there are about 27 QRH checklists that state that the flight crew should PLAN TO LAND AT THE NEAREST SUITABLE AIRPORT. In general the situations requiring the pilots to do this include, but are not limited to:- An engine failure, fire or smoke that continues, only one of the three electrical power sources remaining, only one of the three hydraulic systems remaining, fuel leakages, fuel contamination and structural problems that lead to a loss in cabin pressurization.
On some aircraft, where checklist items are presented electronically on a centralised aircraft monitoring system, the equivalent message will be an amber coloured “LAND ASAP”. In a previous tutorial, the “60 minute rule” was discussed. It is now plain to see where it originated from and why the rules regarding both the adequacy and suitability of en-route airports are so important.
What it means to have to land immediately.
We now go another step further and deeper into the QRH. Since the dangers and horrors of an on-board fire cannot be overemphasised, the checklists related to smoke, fire or fumes start with an initial warning that says A DIVERSION MAY BE NEEDED. Once the procedures to deal with the occurrence are in progress and if it becomes evident that suppression of the problem might not happening as quickly or as successfully as it should be, or maybe even not all, another statement is made…DIVERT TO THE NEAREST SUITABLE AIRPORT WHILE CONTINUING THE CHECKLIST. The task of getting the aircraft safely down onto the ground is now becoming a huge priority. Following on immediately after this statement the QRH says CONSIDER AN IMMEDIATE LANDING IF THE SMOKE, FIRE OR FUMES SITUATION BECOMES UNCONTROLLABE.
The electronic presentation of this message is also simply “LAND ASAP”, but the colour is in red. Either way, both the QRH messages and the electronic messages say the same thing. An immediate landing implies that the adequacy and suitability of airports is no longer an imperative. The first choice should then be to route to a runway, wherever there is one that is long enough but not necessarily wide or strong enough. Within our country, the sort of airfields to aim for would be those such as Parys, Potchefstroom, Witbank, Middleburg, Welkom, Jagersfontein, Beaufort West, Worcester, Plettenburg Bay, Margate…Wherever! In a really severe situation without any reasonable options, the flight crew might need to consider an off-airport landing on such areas as open farmland or a salt pan. Ditching also becomes a viable option, and yes, there is a checklist for ditching!