What is typically required to complete a localizer approach if DME fails?

What is typically required to complete a localizer approach if DME fails?

• A. Only visual references
• B. A secondary navigation method
• C. Timing to establish the MAP
• D. Continued use of DME

Answer: (C)

In a localizer approach where Distance Measuring Equipment (DME) has failed, the standard procedure is to utilize timing to establish the missed approach point (MAP). The localizer provides lateral guidance to the runway, but without DME, the distance to the threshold cannot be determined. To still conduct the approach successfully, pilots rely on timing, which is based on the aircraft's average groundspeed. Timing allows pilots to estimate when they are at the MAP even without the specific distance information that DME would provide. This method is grounded in the understanding that for each aircraft, there is an approximate time required to reach the MAP based on its approach speed. Utilizing visual references or secondary navigation methods might help in some situations, but they are not primary means for establishing the MAP in the absence of DME. Continued reliance on DME is not an option since the question specifies that DME has failed, making timing the most effective procedure for completing the approach safely.

In a localizer approach where Distance Measuring Equipment (DME) has failed, the standard procedure is to utilize timing to establish the missed approach point (MAP). The localizer provides lateral guidance to the runway, but without DME, the distance to the threshold cannot be determined. To still conduct the approach successfully, pilots rely on timing, which is based on the aircraft's average groundspeed.

Timing allows pilots to estimate when they are at the MAP even without the specific distance information that DME would provide. This method is grounded in the understanding that for each aircraft, there is an approximate time required to reach the MAP based on its approach speed.

Utilizing visual references or secondary navigation methods might help in some situations, but they are not primary means for establishing the MAP in the absence of DME. Continued reliance on DME is not an option since the question specifies that DME has failed, making timing the most effective procedure for completing the approach safely.