CFIT, otherwise known as Controlled Flight Into Terrain is a phenomenom that involves an accident in which aircrew flying a perfectly good (at least flyable) aircraft into the ground. What do I mean. CFIT covers those accidents that involve aircraft impacting the ground due to incorrent altimeter settings, loss of situational awareness, or running out of gas (to name a few). Although it is hard to imagine CFIT accidents, they do occur. If you fly IFR or at night, this should be of interest to you. The Flight Safety Foundation put together an incredible package covering Controlled Flight Into Terrain (CFIT). In their research, they analized 40 CFIT accidents that occurred from 1986-1990 to see if any trends were evident. Their findings were pretty clear. Here is a graphical display of their findings. These images come from the FSF CFIT package but I think it is worthwhile to show them on this site in the interest of Flight Safety. So which IFR approach has the greatest risk of CFIT associated with it? Here is what the FSF uncovered...
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The Truth Revealed...
Whenever I show these people instinctively say that it must be while flying an ILS approach because all of the glidepaths appear to parallel the normal 3 degree ILS glideslope. The other people usually say that it must be the NDB/ADF approach. According to the Flight Safety Foundation, the "#1 CFIT Killer" is actually the VOR/DME approach. Why? Multiple step-downs...
Most aircrew use somewhat "standard descent profiles" when completing an instrument approach (obviously this is a relative term) with slight variations when required. So, if you are not vigilant it can be very easy to inadvertently forget to level off from a relatively shallow rate of descent. Take a look at the graphical depiction below and see if it makes sense to you. Notice how almost all of the descent profiles are parallel to the three degree glidepath (which is very close to most descent profiles used during an instrument approach). Also notice how the number increases considerably inside the Final Approach Fix. Hopefully you will remember this in the future. It is very important to remain aware of this type of threat. Next time you begin a VOR/DME approach, think about this and mention it to the other pilot (if there is one...) Maybe they would be interested as well...
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