Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter.
Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.
OCR for page 155
155
CHAPTER 15
Conclusions
The first research phase engaged in multiple studies of dif- have a notable impact on the size and cost of arrestor systems,
ferent topics relevant to developing arrestor alternatives. After irrespective of which passive arrestor technology is used.
identifying promising alternatives, several candidate concepts The FAA EMAS design requirements currently prohibit
were selected for detailed evaluation in the second experimen- damage to the aircraft, which typically results in arrestor bed
tation phase. In the second phase, testing and modeling were designs constrained by the rearward nose-gear loads. More
used to evaluate the performance of the candidates. This chap- aggressive decelerations would be possible if the designs were
ter summarizes important conclusions from both phases of permitted to collapse the nose gear as long as the main gear
research. remained intact. Prior EMAS testing suggests that this may
pose minimal hazards to aircraft occupants. However, aircraft
with low-slung engines could potentially be damaged and/or
15.1. Study Phase
ingest arrestor material in such cases, and the risks of these
The survey of U.S. airport operators revealed that actual effects have not been quantified. Additional concerns would
EMAS costs appear to exceed the predicted values con- apply to turbo-prop aircraft, where propeller damage could
tained in FAA Order 5200.9 in terms of preparatory paving, present additional hazards. It may be advantageous to revisit
installation, and maintenance (Chapter 3). While the survey the requirements regarding landing gear loading in order to
included more airports than the original data set used to create determine if case-by-case exceptions may be permissible. In
Order 5200.9, it did not include all EMAS systems installed at some circumstances, the benefits of aggressive arrestor per-
U.S. airports. It is possible that the average costs could shift formance may outweigh the risks of failing to stop an overrun.
once the remaining airports were included. However, since The approval and commercialization study determined
the survey data for the CTEE was 1.8 times higher than the that the current lack of a general predictive software tool pre-
predicted value, an update to the guidance document may sents a barrier for new entrants to the arrestor system field
be advisable. (Chapter 6). Development of such a tool, or an update of the
A review of aircraft overrun data led to a revised probabil- older ARRESTOR code, could be considered as part of any
ity curve for aircraft overrun exit speeds (Chapter 5). This new approval process.
revised curve indicated that 90% of aircraft overruns may no Although based on anecdotal experience, the researchers
longer take place at or below an exit speed of 70 knots. The have noted a seeming lack of awareness regarding the exis-
new curve suggests that the 90% threshold may have shifted tence, usage, and function of EMAS among airline pilots. This
to just above 80 knots. This could impact the design speeds lack of awareness has been observed in both newer and sea-
for aircraft arrestors if a 90% criterion is to be maintained. soned pilots. It is unclear whether awareness is greater among
Additional investigation may be warranted regarding the pilots that typically land at airports with EMAS. Unfortu-
accuracy of the reported data that was used in the assessment. nately, response from the pilot community was limited dur-
The sensitivity analysis showed that the relative length of ing the survey process. Nevertheless, it may be beneficial to
an arrestor bed will tend to vary with the aircraft exit speed consider pursuit of an educational effort to increase aware-
squared (Chapter 5). Increasing the 70-knot standard exit ness of the existence and function of EMAS within the pilot
speed or the 40-knot minimum exit speed requirements would community.
