In August 2006, the flight crew of a commercial regional jet was cleared for takeoff on Runway 22 but mistakenly lined up and departed on Runway 26, a much shorter runway. As a result, the aircraft crashed off the end of the runway.

There are three major factors that increase the risk of runway confusion and can lead to a wrong runway departure:

Not only can airport complexity contribute to a runway incursion; it can also play a significant role in runway confusion. If you are operating at an unfamiliar airport and need assistance in executing the taxi clearance, do not hesitate to ask ATC for help. Always carry a current airport diagram and trace or highlight your taxi route to the departure runway prior to leaving the ramp.

If you are operating from an airport with runway thresholds in close proximity to one another, exercise extreme caution when taxiing onto the runway. Figure 14-49 shows a perfect example of a taxiway leading to multiple runways that may cause confusion. If departing on Runway 36, ensure that you set your aircraft heading “bug” to 360°, and align your aircraft to the runway heading to avoid departing from the wrong runway. Before adding power, make one last instrument scan to ensure the aircraft heading and runway heading are aligned. Under certain circumstances, it may be necessary to use a runway as a taxiway. For example, during airport construction some taxiways may be closed requiring re-routing of traffic onto runways. In other cases, departing traffic may be required to back taxi on the runway in order to utilize the full runway length.

Since inattention and confusion often are factors contributing to runway incursion, it is important to remain extremely cautious and maintain situational awareness (SA). When instructed to use a runway as a taxiway, do not become confused and take off on the runway you are using as a taxiway.

Title 14 of the Code of Federal Regulations (14 CFR) part 91, section 91.123 requires you to follow all ATC clearances and instructions. Request clarification if you are unsure of the clearance or instruction to be followed. If you are unfamiliar with the airport or unsure of a taxi route, ask ATC for a “progressive taxi.” Progressive taxi requires the controller to provide step-by-step taxi instructions.

The final decision to act on ATC’s instruction rests with you. If you cannot safely comply with any of ATC’s instructions, inform them immediately by using the word “UNABLE.” There is nothing wrong with telling a controller that you are unable to safely comply with the clearance.

Another way to mitigate the risk of runway incursions is to write down all taxi instructions as soon as they are received from ATC. [Figure 14-50] It is also helpful to monitor ATC clearances and instructions that are issued to other aircraft. You should be especially vigilant if another aircraft has a similar sounding call sign so there is no mistake about who ATC is contacting or to whom they are giving instructions and clearances.

Read back your complete ATC clearance with your aircraft call sign. This gives ATC the opportunity to clarify any misunderstandings and ensure that instructions were given to the correct aircraft. If, at any time, there is uncertainty about any ATC instructions or clearances, ask ATC to “say again” or ask for progressive taxi instructions.

The most important sign and marking on the airport is the hold sign and hold marking. These are located on a stub taxiway leading directly to a runway. They depict the holding position or the location where the aircraft is to stop so as not to enter the runway environment. [Figure 14-51] For example,

for Runway 13 and Runway 31.

When ATC issues a “hold short” clearance, you are expected to taxi up to, but not cross any part of the runway holding marking. At a towered airport, runway hold markings should never be crossed without explicit ATC instructions. Do not enter a runway at a towered airport unless instructions are given from ATC to cross, takeoff from, or “line up and wait” on that specific runway.

ATC is required to obtain a read-back from the pilot of all runway “hold short” instructions. Therefore, you must read back the entire clearance and “hold short” instruction, to include runway identifier and your call sign.