You may have come across videos of seemingly crazy crosswind landings, like the ones in the clip below shot in Birmingham, Great Britain, where Storm Ciara has been wreaking havoc with the weather and bringing extremely strong winds.
The BHX airport isfamed for its crosswind landing videos. AvGeeks regularly gather to shoot there on windy days. It looks terrifying, like a lot of those landings and takeoffs are perilously close to disaster. Spoiler: They are not. And well explain why.
Ive seen these videos, and sometimes non-aviation friends will tag me in them, said Shannon Pereira, a Boston-based first officer with JetBlue.
Nine times out of 10, were dealing with a crosswind, she said, noting that it doesnt matter if its a takeoff or a landing. And passengers wont notice. On approach, we are generally pointed in a different direction than perfectly parallel to the runway. This technique is called crabbing into the wind, performed by using the foot pedals to deflect the rudder which works much like a boats and point the nose in the direction the rudder is deflected. Then, as they flare to land raising the nose so that the main gear touches down first the pilots will use the rudder again to align the plane with the runways centerline. Its old hat for Pereira, who flies the Embraer E190.
Obviously, you want to avoid those side loads on the landing gear, but the aircraft can handle it, she said.
The main landing gear of commercial passenger aircraft is locked in position with the longitudinal axis of the aircraft the wheels do not rotate laterally to adjust for a crosswind landing. Several large aircraft such as the Boeing 777 and A380 have main landing gear that can rotate slightly on the ground for ease of taxiing, but not as crosswind compensation for landing. (The B-52 bombersgear can adjust in the air and do just that.)
The View from the Flight Deck
The video below shows the view from the flight deck for a landing at Paris CDG. Whats amazing about this landing is the amount of action on the control column. The pilot is calm, but hes also very focused on the physical task at hand. (You can see it in his face just prior to touchdown.) Pereira said that even though the control column will be moving this much, if you were watching it on the ground you wouldnt see massive adjustments in the planes trajectory.
Wind Shear and Microbursts: The Bottom Falls Out on You
Wind shear is a change in wind speed or direction (or both) over a short distance. It can occur either horizontally or vertically and is most often associated with temperature inversions near the ground, strong surface winds, thunderstorms and rain showers. Wind shear on final approach is typically vertical wind shear. Its flagged for pilots by air traffic control, which has a low-level wind shear alert system on the ground at the airport. Other aircraft and in automatic local weather reports for pilots will also warn of wind shear, which is relatively common.
In the typical scenario with wind shear, the wind will suddenly drop off in speed, by as much as 30 knots. The planes airspeed is measured by its speed relative to the wind, so losing 15 to 30 knots up to 35 mph in an instant is not pleasant. When it happens, it can feel like the bottom of the plane falls out from you.
Wind shear makes a big difference at 100 feet, Pereira said.
Where we know there is wind shear well change the power settings to add more power and less flaps, and come in at a higher speed, she said.
Since 1993, all US commercial aircraft are required to have a wind shear alert system installed, stemming from incidents related to a phenomena called microbursts. Microbursts are particularly dangerous concentrated downdrafts of air and have been the cause of numerous air disasters. In a microburst, a column of wind will descend rapidly over a small surface area, then hit the ground and push outward. The outward push causes a temporary increase in wind speed. But just as quickly, a plane passing through a microburst will hit a downward, violent and constant blast of wind, followed by a tailwind on the way out of the microburst. The consequence can be a loss of control of the aircraft. Fortunately, pilots and ATC work closely to avoid this possibility when landing, giving pilots time to anticipate and extricate themselves from problems.
Thats just what it sounds like: pilots can decide to stop the approach to landing and go around if they feel that conditions are unsafe.
We do a lot of training in the simulators. When the time comes to go around, were not shy, said Pereira. Wed like to land the first time, but there will be good reasons to go around, she said.
Reasons include the aforementioned wind shear and microbursts, but also because of traffic on the runway or so-called unstable approaches, such as where the plane may be too high to descend at a reasonable rate.
Go-arounds can also happen because of loss of separation between the aircraft in front.The DCA River Visual approach into runway 19 [at Washington National] is one such time where it can happen. There, its one take off, followed by one landing. If we are gaining on the runway, the ATC will direct us to turn left or right and climb to a particular heading.
Go-arounds are ultimately a safety measure and not a cause for passenger concern.
The captain has the final call on the go-around. The pilot flying should initiate the call. However, if the first officer is flying and the captain believes the situation unsafe or unstable he or she can call for the go-around and it must be initiated. Once a go-around is initiated you cant abort it, Pereira explained.
To make it easier, aircraft have TO/GA buttons on the throttles. Hitting the TO/GA switch it stands for Take Off / Go Around immediately increases engine power, allowing for a fast exit from whatever situation prompted the go-around.
Pereira speaks with the confidence of an experienced, well-trained pilot one who knows that scary-looking landings are routine, but blue skies dont mean its time to relax:Pilots joke that if its calm and clear out, thats when youll have a crappy landing.
Mike Arnot is the founder of Boarding Pass NYC, a New York-based travel brand, and a private pilot.
Featured image of an Airbus A319 landing in a crosswind in Lisbon, Portugal, by JMF de Almeida / Getty Images