Dangerously low in marginal weather, a Frozen-themed WestJet 737-800 was seconds away from disaster. Fortunately, they broke the error chain. Let’s talk about what could have happened.
On March 7, 2017, WestJet flight 2652 from Toronto to Saint Maarten made some unexpected ‘waves’. The Boeing 737-800 with the famed Frozen livery was flying a non-precision instrument approach to runway 10 in marginal conditions. At the time, the visibility was about a mile and a half with a ceiling of less than 2,000 feet. Conditions weren’t ideal for one of the picturesque photos taken by countless avgeeks at the field but not that unusually for the professional pilots that occupied the seats of that Boeing.
It wasn’t a normal approach though. According to ADS-B data, the 737 briefly touched ‘O feet’ on the ADS-B readout. ADS-B reports altitude in 25 foot increments but have been known to report data inaccurately. That means that at most, the jet was 25 feet above the bay.
From photos and videos on the internet, you can see that the jet was lower than typical as the jet was around a ½ mile from the runway at less than a wingspan’s length above the water. Assuming the jet intended to be on a 3-degree glidepath, it should have been at around 150-200 feet above the water at that point. Instead of completing a successful landing the first time, the jet executed a go-around. Flight 2652 held for an additional 45 minutes and landed safely without further incident.
With no official word from WestJet on the incident, we took a look at footage provided online by ATCpilot.com and one of the St. Maarten spotter cams that is based at the field. The jet definitely looks low for where it was on the approach. The pilots, recognizing that it was an unstable approach (albeit very late in the process), made the right call to execute a go-around.
Without any official press release from the airline or any agency investigation initiated, we’re left to make surmise about what might have happened. As professional ‘avgeeks’ though, were not the traditional media with uninformed pundits spouting crazy conspiracy theories and providing click-bait analysis. It’s way too early to make any declarative judgment of what happened and we’re not surfacing this story to assign blame. When incidents like this happen though, professional pilots should ‘hangar talk’ about the scenario to think through how something like this could easily happen to them too and how to avoid a similar incident in the future. Here are three of the most likely scenarios of why WestJet’s Frozen bird could have came so close to a CFIT (Controlled Flight into Terrain).
1.) Task saturation and automation error while searching for the field
With visibility less than 2 miles, flight 2652 was most likely flying a GPS or VOR approach to runway 10. A non-precision approach is something that every commercial pilot must be able to do. (Non-precision means that there is course guidance but not vertical guidance) However, most commercial airports these days have precision approaches meaning that commercial pilots rarely get to practice these types of approaches except in a simulator. In this case, the pilots could have neglected to set a level off altitude as they dialed in a descent rate. When they arrived at the MDA (Minimum descent altitude), they could have continued to search ‘outside the cockpit’ for the runway. With a murky, indefinite-horizon sky (that looked like a combination of dark blue and grey), they could have continued the incipient descent without realizing it only to finally execute a go around because of declaring a missed approach without seeing the field or recognizing how low they were either by visual cue or audible alert (landing ‘100’ feet radar altimeter call out).
2.) Setting the wrong altimeter setting
While much less likely, the crew could have set the wrong altimeter setting on arrival. This means that the crew could have leveled off at their MDA but their actual altitude was significantly below the expected altitude. This situation is a stretch and not very likely. The altimeter setting was actually higher than the standard 29.92 meaning that they would have been high on the approach if they failed to reset it when passing through transition altitude. The only way this situation is a possibility is if they misheard the altimeter setting and dialed in a completely erroneous setting. While possible, it is also highly unlikely that they wouldn’t have caught the error on intermediate level offs that took place throughout the arrival. Pilots have addition tools like a radar altimeter that would have revealed such error.
3.) Wind shear
A very low approach like this could possibly be explained by a very strong wind shear. Strong wind shear has been known to cause rapid decay of airspeed and altitude on approach. Delta flight 191 crashed because of a strong wind shear back in the 1980s. In this case though, the FlightRadar24 data doesn’t show any rapid descents or drastic speed changes (other than a slow ground speed). Aircraft landed at the field before the WestJet 737 without incident and no shear was reported. Still though, storms were in the area and the video footage shows winds near the field were strong enough to cause rippling in the bar patio umbrellas that were seen in the first go around video. Winds aloft could have been much stronger. One other indication that makes this situation plausible is that the gear was not immediately retracted on the go around. That could have been intentional or an oversight during a rattling situation of a normal go-around after almost impacting the water short of the field.
It’s all just speculation at this point but we shouldn’t shy away from discussing ways to become safer aviators.
It’s easy to Monday morning quarterback the situation. And the truth is that at this point the only people who know exactly what happened are the pilots and anyone that they spoke to after safely landing. Despite great technology, improved cockpit resource management, and training, mistakes do still happen. If this was just a mistake, everyone is fortunate that there was no damage besides a bruised ego and a probable chat with the chief pilot.
Unfortunately for the WestJet pilots’ sake, the mistake happened near one of the most photographed/videoed airports in the world. It’s a reminder to all professional aviators that in this era of smart phones and social media, every flight is just one tap away from the rest of the world seeing it. Fly safe out there…
Editors note: Thanks to ATCPilot.com for the footage and screenshot.