In January 2016, ANAC published Flight Alert AV No. 01/2016, addressed to air taxi companies and to pilots operating under RBAC 135 (Brazil's equivalent of FAR Part 135). The case behind the alert is short to tell. A Cessna 560 left Congonhas for Jacarepaguá with two pilots and one passenger. It landed, used brakes and thrust reversers, and stopped about 200 meters past the far end of the runway, on the grass strip. Nobody was injured, the aircraft was not damaged, and the occurrence was classified as a serious incident.
What the alert describes next is the script of almost every runway excursion in business aviation. The manufacturer's table called for 701 meters for a full stop, with the aircraft stabilized on final. Observers reported high speed and height on the approach, and touchdown came abeam the tower, with 450 meters of runway ahead. Add the 450 meters of runway to the 200 meters of grass and you get 650 meters: practically the distance in the table. The airplane did the math right. It just started in the wrong place.
The 60% rule that never made it into the planning
There is a second point in the alert, and it comes before the landing. Because it was an air taxi flight, the planning should have considered item 135.385 of RBAC 135, which requires turbine-powered transport category airplanes to be able to make a full-stop landing at the destination within 60% of the effective runway length. This is the so-called runway factoring: the remaining 40% is margin.
With a landing distance of 701 meters, the required runway was 1,168 meters. Jacarepaguá had 900. The crew was scheduled to land on a runway shorter than the rule allowed for that type of operation, and the investigation records that the landing limit at the destination was not considered in the planning of the leg.
The regulatory margin exists precisely to absorb what happened afterward: a fast approach, a long touchdown. When the planning has already consumed the margin, the approach has to be perfect. And the approach rarely is.
What a stabilized approach is
The definition is not an instructor's opinion. The FAA, in AC 91-79A on mitigating landing excursions, and the Flight Safety Foundation, in the ALAR Briefing Notes, converge on the same elements:
- Full landing configuration early: gear down, landing flaps, trim set, landing checklist complete.
- Stabilized by the window: before crossing 1,000 ft above the touchdown zone in instrument conditions, or 500 ft in visual conditions.
- On the correct lateral and vertical path, with a 3-degree glidepath (or the published one), requiring only normal corrections. Large corrections, by definition, are not a stabilized approach.
- At approach speed, within the range the manual defines.
- Descent rate compatible with the glidepath and the ground speed.
- Power set to maintain all of this, not at idle.
The rule that closes the list is the most important one: if the approach is not stabilized in the window, the action is to go around. It is not to correct and see. AC 91-79A is explicit in saying that an approach requiring abnormal corrections does not meet the concept, and that the go-around must be initiated.
Why the jet lands fast and long
The two failures the ANAC alert points to, high speed and high height, have a known effect on landing distance. The numbers below come from AC 91-79A itself, which in turn cites the Flight Safety Foundation and the FAA's Pilot's Handbook.
Speed. Crossing the threshold 10% faster increases landing distance by 20%, and that assumes a normal flare and touchdown on the aiming point. If the pilot lets the airplane float to "burn off" the speed, the increase is greater, because every second of float at 120 knots is about 60 meters of runway passing under the airplane without braking anything.
Long touchdown. The manual's distances assume touchdown at the certification point. AC 91-79A recalls that the typical operational touchdown point is in the first third of the runway, often beyond the 1,000 ft aiming point marks, and that this difference needs to be factored into the landing distance assessment at arrival. In jets, the guidance is to land the airplane, not hold it off the ground: a firm landing is normal and desirable.
Height. Certified distances start from 50 ft over the threshold. Crossing higher moves the touchdown point down the runway before the airplane even touches.
Tailwind. The first 10 knots of tailwind increase landing distance by 21%. For small airplanes, whose manuals often carry no tailwind data, the FAA cites manufacturers that recommend adding 10% for every 2 knots.
Slope. Each 1% of downhill runway slope increases the distance by 10%, and many manuals only consider gradients above 2%.
Each factor, alone, seems absorbable by the spare margin. Combined on an afternoon with a wet runway, a passenger waiting and a distant alternate, they become the Jacarepaguá case.
The number that explains everything: 3%
The Flight Safety Foundation spent six years studying the go-around. The final report of the Go-Around Decision-Making and Execution Project, published in 2017 and led by the Presage Group, begins with two findings that should hang on the wall of every dispatch room:
- Failing to go around is risk factor number 1 in approach and landing accidents, and the number 1 cause of runway excursions.
- Unstabilized approaches happen in 3.5% to 4% of all approaches, and 95% to 97% of the crews in that situation continue to land. Put another way: about 3% of unstabilized approaches end in a go-around, even though company policy says to go around.
A Foundation study of its own covering 16 years of runway excursions concluded that 83% of them could have been avoided with a decision to go around. And there is a figure that bothers anyone who thinks the problem is only the approach: a little over half of landing excursions came after a stabilized approach. The flight became unstable in the float, in the long touchdown, in late braking. The go-around, in those cases, was still possible until touchdown, and was not made.
The report is direct about the reason. It is not a lack of policy: almost every company has one. It is that the crew does not believe the approach is outside the criteria to the point of justifying the go-around, the policy is seen as theoretical, and management does not know the real compliance rate of its pilots, because it does not measure it. Without measurement, the policy is text in a manual.
What separates the written policy from the decision in the air
For the operations manager of an air taxi or business fleet, the lesson of the ANAC alert and the Foundation report fits in five practices:
- Runway factoring in planning, not in the briefing. If the destination runway does not accommodate the RBAC 135 60% with the expected weight, the flight should not be scheduled there. That is a decision for dispatch and management, not for the pilot on final.
- Reassess landing distance on arrival, with the actual wind, runway and weight, and apply the 15% margin the FAA recommends in SAFO 06012. The article on takeoff and landing performance shows how each variable enters that calculation.
- Stabilization window with a mandatory callout. At 1,000 ft or 500 ft, the monitoring pilot declares "stabilized" or "not stabilized." Not stabilized means go-around, no debate.
- Go-around without consequences. Pilots continue because going around costs explanation, fuel and delay. The company that treats the go-around as a normal procedure, and logs it as a learning event and not a failure, changes the statistic.
- Measure. How many unstabilized approaches were there this month? How many go-arounds? If the answer is "none," the company is among the 97%, not among the 3%.
Where Alis comes in
The decision to go around belongs to the pilot in command, in the air, and no system replaces it. What Alis does is remove from its path what can be resolved before and after the flight. In Flight Kit, the runway dimensions and airport elevation sit next to the estimated landing weight and the weather, so that the short runway shows up in the planning, and not on final. The FRAT incorporates the threats reported by other operators at the same airport: short runway, downslope, no overrun area. And the company's SMS (SGSO) records the go-around as what it is, a prevention event, so that the compliance rate is a known number and not an assumption.
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This article is informational. The case described is that of ANAC Flight Alert AV No. 01/2016, as published; the landing distance percentages are those of the FAA's AC 91-79A, which cites the Flight Safety Foundation and the Pilot's Handbook of Aeronautical Knowledge, and serve as an order of magnitude; the go-around statistics are from the final report of the Go-Around Decision-Making and Execution Project (Flight Safety Foundation, 2017). The text does not replace consulting RBAC 135, the aircraft's approved flight manual, or the guidance of the person responsible for operations.