Three years ago today, I attended a one-day workshop regarding stabilized approaches.
The event was hosted by Air Canada and Porter Airlines. It was held about a year after Porter and a few months after Air Canada started implementing the Flight Safety Foundation’s (FSF) criteria for stabilized approaches.
To date runway excursion is the most common aviation accident. There are currently no technological solutions. EMAS is one, Engineered Material Arresting System Light concrete that collapse under the weight of an aircraft and preventing the aircraft from overrunning the edge of the runway by much. It is implemented almost solely in the USA on runways shorter than 8000 feet. This implies that the main mitigation for runway excursion is to make long runways.
This still does not prevent short-of-the-runway landings, veer-offs and is not always possible.
The solution the industry came up with is called “stabilized approach” SAp. The idea is that if you are fully ready in terms of checklist, configuration, flight path and energy management some time before landing, you highly increase the chances of a successful landing. Most of the regulators mandate stabilized approach. The CAA will not set the criteria for it – this is up to the operator.
The FSF recommended for many years being stabilized at 1000 feet AGL in IMC and 500 feet in VMC. The results were great about 97% of all approaches are stabilized on average.
The problem is that out of the un-stabilized most pilots will not go around. Some of the reasons are that missed approach is by far the most complicated maneuver during normal flight as it involves mental change, configuration, and power changes as well as flight path changes. It is by a large margin the least trained phase of flight (we land every flight we go-around 2-4 every 1000 flights on average. Pilots therefore feel less comfortable going around than during any other maneuver.
The FSF conducted a study with interesting conclusions and recommendations. The study is called “Go around Decision Making and Execution” and can be read here.
The study involved a rather big group of pilots. The findings include but are not limited to:
- Managements do not enforce a strict go around from an au-stabilized approach.
- Pilots and management pilots perceive 1000 feet above the threshold to be too high and that there is enough time to correct what needs to be corrected. 1000 feet is about a minute and fifteen seconds.
- Pilots have a subliminal unwillingness to go around due to continuation bias and the lack of proper training in going around.
- An approach that was stabilized at 1000 feet and then became un-stabilized is harder to detect and deal with.
The FSF recommendations include but are not limited to:
- Operators should adopt a “no-fault go-around policy”
- Operators should lower the “stabilized approach gates”
- The target and limit for stabilization should be separate. Just like minimums, whee you get an “approaching minimums” callout and TCAS you get Traffic Advisory before you get Resolution Advisory, the same logic dictates separating the target of stabilization from the limit.
- The FSF came up with their recommendation for Stabilized approach criteria. But the limit for stabilization is recommended now to be at 300 feet.
- This should result in less missed approaches
- More correct decisions to go around
- Less un stabilized approaches continuing for landing.
The status as of February 2022 is that the new Stabilized approach is still tagged as “for industry validation” and not “recommended criteria for a stabilized approach”.
IATA are still using the 1000/500 in their IOSA ISARPs and audits. This is a big deterrent as operators have to deal with IOSA findings.
I do not know how many companies have adopted these new guidelines.
We did a version of the recommendation following a workgroup and simulator validation.
Check out the study.