Bombs Away?

1

• Bombs Away?
• Explosions aboard Commercial Aircraft
• Arnold Barnett
• MIT, LFM

2

• No rational person would say that we should pay
  any price, however enormous, to achieve any
  increase in security, however minuscule.

3

• Still, some recent US security decisions are
  hard to understand.

4
Why is air cargo-- very little of which is
screened for explosives --transported aboard US
passenger jets?
5
If cargo were banned from passenger jets, the
profit that the airlines get from transporting
freight could be covered by a 2 user fee per
passenger.
6
Suppose that air travelers were asked

• Would you be willing to pay 2 more per trip to
  travel in a jet that is not carrying cargo
  unscreened for explosives?
• What do you think the answer would be?

7
Why did they end positive passenger bag match
(PPBM) when explosives detectors were introduced
to inspect checked luggage?
8
Absent PPBM, the explosives detector becomes
something of a roulette wheel, which it costs
almost nothing to play and with a chance of
winning equal to the false negative rate of the
machine (which is not zero).
9
When US carriers performed PPBM in 2002

• 1.2 of departures were delayed because of the
  policy
• Among those flights that were affected, the mean
  departure delay was 10 minutes.
• The dollar costs associated with the policy
  averaged about 10 cents per boarding passenger.

10
But is PPBM no longer cost-effective?
11
Things have changed recently, because of the 25
increase in the amount of checked luggage on US
domestic flights.
12
This increase in checked luggage would be
expected to have a larger-than-linear effect on
bag-match delays

• One might expect a 25 rise in the probability
  a bag-pull would be needed.
• Because there are 25 more bags in the luggage
  hold, the time to extract a bag might grow by
  roughly 25.

13
Moreover, the doubling of fuel prices since 2002
presumably has a comparable effect on the dollar
cost per minute of departure delay at the gate.
14
Revised PPBM Statistics

• Probability of Delay Grows from 1.2 to 1.5.
• Mean PPBM Delay Given that One Occurs Grows from
  10 minutes to 13 minutes.
• Mean dollar cost of PPBM per passenger boarding
  grows from 10 to 15 cents.

15
Are we willing to pay this price to keep
unaccompanied luggage off originating
flights?(Under certain ATA statistics, PPBM
would be cost-effective if it prevented one
successful bombing every 50 years.)
16
Proposals for new measures to prevent airborne
explosions are popping up everywhere.
17
Separating people from their laptops would be
painful, although some people could surely use
the time to go over reading material, or even
revert to pen and paper.For now, the surest
way to keep dangerous materials out of the cabin
is to keep virtually all materials out of the
cabin. The New York Times, 9/10/06
18
Are they crazy?
19

• Are we doing enough emergency planning to
  prevent on-board explosions that might be
  imminent?

20
Suppose that a jet plane has suddenly plunged
from the sky, for reasons unknown.

• What should we do, knowing that terrorist acts
  against transportation often are followed by
  others within minutes?

21
One possibility

• Immediately order all planes above 10,000
  feet to descend to that altitude, where they
  would have a reasonable chance of surviving an
  on-board explosion (better than 50/50).

22
Calculations and Common Sense Make Clear Some
Realities

• From the moment of the first explosion to the
  issuance of the descend immediately command, at
  least three minutes would elapse.

23

• If a jet at 30,000 feet received such a command
  and began descending immediately at the maximum
  safe angle (15º, according to Air Transport
  Association), it would require two minutes to
  reach 10,000 feet.

24

• Thus, a minimum of five minutes would elapse
  between the initial event and the arrivals of
  endangered jets at a reasonably safe altitude.

25
Major Fatal Terrorist Bombings Against Air/Rail
Since 9/11

• Year Location Number of Attacks
• 2003 Madrid 10 within 3 minutes
• 2004 Moscow One
• 2004 Russia One
• 2004 Russia 2 within 2 minutes
• 2005 London 3 within 1 minute
• 2006 Mumbai 7 within 11 minutes

26
In other words

• Based on the degree of simultaneity in these six
  events, perhaps two of the 18 follow-up bombings
  could have been thwarted in the sky, given a
  5-minute response time. This works out to an
  average of 0.33 jets saved per event.

27

• But, of course, there is collision risk when
  large numbers of planes descend at once towards
  the same altitude.

28

• Calculations based on geometrical probability
  indicate that, if a jet undertook an unannounced
  emergency descent from 36,000 feet to 10,000 feet
  without changing direction, the chance it would
  collide with some other plane at some lower
  altitude could sometimes approach 1 in 100 (!).

29
Even assuming some strategy under which planes at
differing altitudes descended at different angles

• It is hard to see how average loss to collisions
  would fall below 0.5 jets per alarm. And some
  of the alarms that led to descend immediately
  commands would be false.

30
Tragically, therefore, the optimal strategy
given the sudden loss of a jet might well be

• Do nothing
• .except hope.

31

• Why are we going ahead with a Trusted Travelers
  program?

32

• Under the original plan, Trusted Travelers
  would submit to background checks and biometric
  processing. In return, they would get expedited
  screening and less stringent physical security at
  airports.

33

• As a practical matter, the only applicants for
  trusted traveler status who would be denied it
  would be those who lied flagrantly on their
  applications or were on terrorist watch lists.

34

• Indeed, in the trial run program now in use
  at Orlando, 23,000 people have applied for
  Trusted Traveler status. You can count on both
  hands the number of applicants who have been
  rejected.
• New York Times, May 16, 2006

35

• Thus, sleeper terrorists (like the London
  Underground bombers) who successfully attained
  trusted-traveler status could come to the airport
  guaranteed in advance that their security
  screening will be limited.

36

• The risks inherent in the trusted-traveler
  program are especially unfortunate because its
  main objectives could be met without any
  reduction in security.

37
TSA has apparently become much more reasonable on
this issue recently. But, under its latest
stated position, the biometrics and the
background checks have no logical rationale.
38

• So, where are we?