4.2.3. Phase of Flight

Figure 3 shows the distribution of accidents with maintenance contributions by phase of flight. The reason for recoding the phase of flight from the original ICAO codes is that a number of maintenance related issues manifest themselves prior to causing 'the accident'. For example, gear related issues

manifest themselves at takeoff (gear up) or approach (gear down), but the 'accident' is considered to have occurred upon landing. When the phase of flight as coded by ICAO was utilized (Figure 3a), no statistically significant result is observed (not included in Section 4.1), although there is a slight excess of landing accidents, again expected by the fact that maintenance issues are most commonly associated with the landing gear. When recoded (Figure 3b), the results are statistically significantly different (as shown in Section 4.1). As hypothesized, there are more accidents during climb; however, there is no increase during takeoff. Again, during climb (ICL) is when the gear is retracted, and this spike corresponds to these failures occurring at that time.

**Figure 3.** Distribution of phase of flight for accidents with maintenance contributions: (**a**) the phase in which the accident occurred (end result); (**b**) the phase in which the maintenance issue manifested.
