Expectation Bias Can Cause Incidents—or Worse

“What’s it doing now?” If you haven’t said or thought it in the cockpit, you’ve almost certainly heard it from someone else. The question often has to do with new technology in the cockpit or automation not doing what you think it should. With more and more advanced systems—particularly with regards to navigation—expectation bias is a problem that can easily cause pilot deviations, or worse. Screens and automated systems are only one aspect of flying where expectation bias can bite you. It can rear its ugly head nearly any time you fly, whether commercial or GA, IFR or VFR.

Expectation bias is the belief that you know what is going to happen without preparing for changes that might occur. It’s just as likely to affect experienced pilots as newly minted ones. Unusual ATC clearances and instructions can fall on deaf ears; our confusing notam system can make it challenging to catch changes to procedures; equipment failures can surprise you; and forecast weather patterns can change. When the unexpected happens, you need to be ready.

Around 6 a.m. on August 27, 2006, Comair Flight 5191 was scheduled to depart from the Blue Grass Airport (KLEX) in Lexington, Kentucky. The pilots, flying a Bombardier CRJ100, were cleared for takeoff from the 7,003-foot-long Runway 22. The taxiway leading from the terminal to Runway 22 crossed Runway 26, which was only about half the length of the planned departure runway. Rather than crossing the approach end of Runway 26, the pilots rolled on to its centerline, mistaking it for the longer runway. They didn’t realize their mistake until it was much too late. The takeoff resulted in a devastating crash, killing everyone except for the first officer. While this was clearly pilot error, the airport has since been reconfigured. Runway 26 was removed and replaced with a new runway, 9/27, which does not intersect Runway 4/22.

While many factors contributed to this tragic accident, expectation bias was a major component. The pilots saw a runway and expected it to be the one they were cleared to take off from. Had they paid more attention to the airport diagram or looked at their heading as they rolled onto the centerline, they could have prevented the accident. The heading bug is also a great tool during approaches, or on final, to make sure you’re lined up for the right runway.

Intersecting runways can present other threats, particularly at uncontrolled airports. In 2018, a Cessna 150 and Cessna Citation jet collided at Marion Municipal Airport (KMZZ) in Marion, Indiana. According to the National Transportation Safety Board report, it appears that the Citation pilot expected no other traffic to be in the area. No calls were made on the common traffic advisory frequency as the jet approached Runway 22. The Cessna 150 pilot, however, announced his departure over the CTAF on Runway 15.

The 150 started its takeoff roll from 15 as the Citation made a straight-in approach to 22—another uncontrolled airport offense. The two-seater impacted the jet before it was able to lift off, killing both occupants.

While terminal aerodrome forecasts are generally quite reliable, weather still can be unpredictable. The fix is straightforward: Don’t expect the weather to be as good as forecast. Plan for the worst. Low ceilings and visibilities are not the only considerations that likely could cause a diversion if you’re not able to complete or accept an instrument approach.

Unforecast weather can also affect your fuel situation. You might expect to have plenty of fuel to get to your destination, but keep a close eye on the flight time. Headwinds might dwindle down your fuel reserve to nothing, and if you have to divert around a thunderstorm, you should definitely consider landing to top off the tanks.

Unexpected wake turbulence and wind shear can greatly affect the stability of the airplane. Even if you don’t get a warning from ATC about wake turbulence and wind shear, you should be ready for air-flow disturbances. A nice, smooth approach might lead you to believe that the conditions will continue all the way until the runway. Instead, expect your perfect approach to suddenly turn nasty. The readiness to add a quick boost of power or timely control input can save you if you encounter a big wind shift near the ground.

IFR flight plans can comprise a long list of fixes, including standard departure and arrival procedures, en route fixes, and approaches. Standard operating procedures used by airlines require both pilots to thoroughly analyze notams and the IFR clearance for each flight, as well as confirm all of the fixes and altitudes in the FMS. This practice reduces the chance of errors because there are two sets of eyes on each step of the clearance and data entry.

If you’re flying by yourself, it’s important to be extra vigilant with the data entry. Don’t assume that the FMS you use correctly enters all the fixes for the departure procedure, arrival or approach. And the charts might not have the correct information either. Minimum decision altitudes (MDAs), decision altitudes (DAs) and other details often change through notams.

In addition to ensuring correct data entry, the briefing procedure used in the airlines mentally prepares the pilots for the flight. More-complex airports demand plans for several possibilities. However, sometimes best intentions are not sufficient and expectations turn to surprises. This happened on my recent flight into Dallas-Fort Worth International Airport (KDFW).

KDFW has seven runways. Relying on past experience, the captain and I both expected either Runway 17L or 17C. We briefed the approaches and taxi procedures for each. However, as we approached the airport, the controller surprised us with Runway 13R. It was a bit of a scramble to re-brief, modify the FMS setup and talk about the taxi procedures. We had enough time, but we would have asked for delay vectors or a hold if time had been too tight.

Expectation bias got us again on the ground. ATC instructed us to use Taxiway Bravo to Terminal Echo. The captain insisted that we were supposed to taxi on Alpha, the more common route from west to east. A quick call to the ground controller cleared up the instruction. While unusual, the controller wanted us on Taxiway Bravo—a good reminder that it’s worth verifying with ATC if you get instructions that you don’t expect or don’t make sense.

Some newer audio panels include the ability to replay radio transmissions to verify the actual assignments. This can be extremely useful and eliminates the need to call back to a busy controller. However, if you don’t have the ability to replay, it’s critical that you are absolutely certain about the clearance. While the controller might be slightly annoyed at having to restate the clearance, this annoyance is preferred to a possible deviation, incident or accident.

Read More: from Pia Bergqvist

Instrument procedures require careful attention. Departure and arrival procedures in particular can be tricky. In most cases, step-down fixes on arrival and approach procedures clear the aircraft to cross at or above a given altitude—but never expect it. On the SUUTR3 arrival into Sacramento International Airport (KSMF), for example, it’s easy to be fooled by the FOOLZ fix, which is at or below FL 210 while most fixes prior are at or above. The previous fix, SUUTR, is between FL260 and FL 240, requiring a fairly steep drop in just 10 miles.

You also can’t expect all of the pertinent information to be on the chart. Multiple speed restrictions are posted on the HLYWD1 arrival into Los Angeles International Airport (KLAX). But once you get onto the approach phase, the 250-knot restriction is implied below 10,000 feet. Most of the time, pilots have to be aware of this, but when the previous procedure tells you what speed to fly, the 250-knot restriction is an easy expectation-bias “gotcha” even for experienced pilots.

In busy airspace, ATC generally provides vectors onto instrument approaches. On a quick trip from San Diego to KLAX—presenting a heavy workload in a commercial jet—expectation bias bit me again. I had loaded the ILS 25L approach into the FMS with vectors going into KLAX. As we approached the Seal Beach VOR, the controller cleared us to TRNDO for the ILS 25L approach, rather than vectors. The captain and I had to reprogram the FMS while already being under a heavy workload.

One expectation that will likely fall short in most cases—but one that should always be considered—is the missed approach or go-around. What if the clouds are lower than forecast? What if there is an animal or some debris on the runway that you don’t see until the last second? What if the tower instructs you to go around on short final? Running over the procedure for the go-around/missed approach as you near the destination is a habit you should perform proudly. Be ready to power up, pitch up, clean up and climb up—and know the procedure that is specific to your airplane.

During Category II approaches, which have decision heights as low as 100 feet above the touchdown-zone elevation, the first officer flies the approach, but the captain lands the airplane. The reasoning behind this is that if the runway is not seen at the DH, the FO flies the missed approach. If the runway environment is in sight, the captain lands the airplane. So, during the entire approach, the FO expects to go missed while the captain expects to land. Both are fully prepared for each scenario so the decision can be made at the last second without confusion.

One of the most common cases of expectation bias is autopilot mismanagement. You might expect the autopilot to turn toward a certain fix or level off at an altitude. But if it doesn’t, you can quickly get into a scenario that will not only get you into trouble with ATC and/or the FAA but can turn you right into a mountain. Never fly an airplane into IMC conditions unless you fully understand how to manage and analyze the automation you have available. Always verify that the procedure you have loaded is actually activated. When you are vectored, it’s not enough to change the heading bug. Make sure you change from NAV mode to heading (HDG). Check that the airplane is climbing when you’ve commanded it to climb. When the autopilot levels off from a descent, make sure you add power so the autopilot doesn’t lead you into a stall. Don’t expect it to do what you want it to do. Double-check the mode, flight path, altitude and speed.

Just like missed approaches and go-arounds, equipment failures are rare. But it would be a big mistake to expect all equipment to continue to function. It’s better to expect and prepare for a failure.

Writing down ATC frequencies when controllers change might seem redundant, but I experienced a perfect scenario that reinforced this habit. I was flying one of my very first flights after the 9/11 shutdown in fall 2001. My student was a private pilot candidate working on the cross-country phase of training. Because all flights had to be on an IFR flight plan at that time, we simulated a VFR cross-country under IFR rules from Santa Monica Municipal Airport (KSMO) to McClellan-Palomar Airport (KCRQ) in Carlsbad, California.

As we approached the Oceanside VOR (OCN), several items on the Cessna 172 panel went black—including the radio we were communicating on. An electric bus circuit breaker, located on the engine side of the panel, had popped. Fortunately, the second radio was still lit up, and I had written down the last frequency. I quickly entered and activated it, but in the few seconds we were off frequency, the controller had apparently attempted to reach us. A frantic female voice was calling our N-number. She was thankful that I responded as quickly as I did, and I was very thankful that I had prepared for the unexpected.

Safe flying requires expectation and planning. You can expect the best scenario, but you should plan for the worst. When your expectations don’t materialize, be flexible and willing to ask for help if you need more time to create a new plan. Ask for delaying vectors. Ask for a hold. Expectation bias will bite you when you aren’t willing or able to make changes to the plan. In some cases, you don’t have much time for the initial startle. Be prepared.

Verify runway: Critical items, such as the runway you’re rolling onto or lining up with, should always be verified. Whether you’re about to take off or land, the easiest way to verify that you’re on the expected runway is to look at the heading. If it doesn’t match the numbers on the runway, go around or abort the takeoff.

Verify clearance: If you’re not entirely sure about what a clearance means, ask for clarification. Don’t ever be afraid to ask questions of the controllers, whether on the ground or in the air.

Verify chart: When briefing a chart, look for possible “gotchas.” Are all step-down fixes “at or above,” or are some “at or below?” Has anything changed in the latest update? Don’t expect all fixes and altitudes to be the same as the previous time you flew. Did you check the notams? Critical info such as the decision altitude/height or MDA could have changed.

Verify automation: Avoid the “what’s it doing now?” scenario by verifying that the autopilot modes you want are active. Are you following a flight plan? Make sure the autopilot is in NAV mode. Are you being vectored? HDG mode. Are you cleared for a higher altitude? Set your climb mode, and don’t forget to add power.

Verify weather: While TAFs are often quite accurate, you can’t always trust that they will give you a perfect picture of the weather. Pay attention to the trends, and if the weather is not what you expect, take a conservative approach by either diverting around the weather or landing and assessing the actual situation.

Verify missed approach: Always be ready to go missed. During the final part of the approach, mentally go over the first few steps of the missed approach procedure so you’re ready in the event that you don’t see the runway. If you’re VFR, be ready for a go-around at any time.

This story appeared in the March 2021 issue of Flying Magazine