Non-normal checklists don't always cover the situation

Non-normal checklists don’t always cover the situation

04.08.2020 , David Jacobson , from-our-logbooks 0

Non-normal checklists don’t always cover the situation

Throughout an aviation career spanning 55 years and 24,500 hours, a pilot is bound to encounter some non-normal situations along the way. Licence renewal checks, conducted in the modern and very sophisticated digital flight simulators offer fantastic, accelerated learning experiences for pilots at all levels, with zero safety risk to crews and airplanes. However, unless a company flight training department – or an individual flight instructor/examiner – has some imagination, most exercises rely heavily on the manufacturer’s Quick Reference Handbook (QRH) and its unique and quite definitive Non-Normal checklists for the airplane type.

The non-normal events that I experienced, over that 55-year period, were more often than not either a combination of issues from more than one system, or an issue out of ‘left field‘, that did not match, exactly, any non-normal checklist. The ability of pilots to think ‘outside the square’ is a definite advantage.

This is the fifth article in a planned occasional series, sharing some most memorable and treasured experiences. This one is also from my own career : We do plan to feature other, highly esteemed pilot friends and colleagues, who are only too willing to share their collective aviation experience. The crucial lessons that we learned along the way are just as valid today. They contribute, in no small way, to that intangible but essential quality known in aviation as ‘airmanship’.

A great example of this is a non-normal landing I once executed at Adelaide, South Australia, in a B737-400. On approach to runway 23, flaps 1º extended perfectly normally, with correct indications for both leading and trailing edge flaps. On selection of flaps 5º, The flap gauge L & R needles ’stuck’, just as the second stage, Flaps 5º was running. The anticipated change in trim seemed to suggest that the flaps had run to 5º, but my First Officer and I couldn’t confirm this on the flap gauge. Further, the B737 flap asymmetry protection system takes its signals from the L and R flap gauge needles – and the gauge was now u/s. The leading edge devices were confirmed as fully extended by their separate LED indicators and, cross-checking attitude, airspeed and thrust setting, we believed that we probably had trailing edge flaps at 5º. We just couldn’t confirm this, as there are no painted ‘witness’ position calibration marks presented on the flaps, as they extend.

After referring to the Non-normal checklists, we established that there wasn’t a dedicated procedure for this particular issue. On conferring with our company engineers by radio, we decided it was prudent NOT to attempt any further flap extension or retraction in the air (in case of any uncontrollable flap asymmetry), and to make the conservative assumption that the trailing edge flaps were fully ‘up’, i.e., 0º and execute a Trailing Edge Flaps-Up landing, as per the non-normal landing checklist for that condition.

At our landing weight, the Vref 40 (1.3 Vs for Flaps 40) airspeed was 136 KIAS. Adding 5kts made the VApp airspeed 141 KIAS. With the trailing edge flaps at 0º, the further additive for the higher Vs was another 40 kts, so we made our final approach at 181 KIAS! That looked pretty fast, as we crossed the threshold.

I aimed at the standard B737 aiming point, at 1000ft from the threshold and flared as the glare shield passed the 500ft point – same as for a normal Flaps 30º or 40º, utilising my own ‘Jacobson Flare’ technique. The only correction I needed to make was to position the aim point 1 LOWER in the windscreen, due the much higher nose-up body angle (8-9º, instead of the usual 2.5-3º nose-up), using the autopilot-coupled ILS to confirm both glide path and visual eye path.

We actually touched down in the pre-determined spot – aiming point 1 – same as any JF landing and I rolled through to the full length of the runway, to spare the brakes, wheels and tyres from excessive heat – and to take full advantage of the Aviation Rescue and Fire Fighting units we had requested to attend, to deal with the possible event of any tyre or brake failure or fire. When we shut down, the brakes were probably cooler than for a normal landing, when we might brake more heavily, to make a designated runway exit taxyway. On turn-around, the flap indicator gauge was replaced and the issue was resolved.

The lessons learned and offered are that:

1. Sometimes, a non-normal event doesn’t exactly match a published non-normal procedure.

2. The Jacobson Flare self-compensates for these non-normal flap configurations and airspeeds. Just remember that the aim point position in the windscreen might vary from its usual position for a normal landing, due to a different airplane body angle caused by the different flap configuration. The longitudinal flare fix of the Jacobson Flare also self-compensates, automatically, for uphill- and downhill-sloping runways, approach path angle variations and the classic cause of flare ‘height‘ illusions, runway widths different from those of our more familiar airports.

Wishing you many safe landings

Captain David M Jacobson FRAeS MAP

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Non-normal checklists don’t always cover the situation