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Pg. 3, Reason to Revise
Reasoning of ACRP Reports
Page 4, Approach
Page 5, Review Historical Basis
Page 5, Review Historical Basis GBA 1971 Pg. 11
Page 5, Review Historical Basis GBA 1971 Pg. 11
Page 5, Review
Historical Basis GBA
1971 – Response Map
Page 5, Review Historical Basis GBA 1971 –
Response MapALARM REACTION TIME FURTHEST POINT TIME
20 Seconds 3m 17s/5m 12s
Q1 = PCA x R x T, where:
PCA = (0.67) TCA, TCA = L (K + W), and
L = length of aircraftW = width of fuselageR = application rate of selected agentT = time of application (1 minute)
- p.47
ARAC 2004 –
Page 5, Review Historical Basis
Page 5, Review Historical Basis
ARAC 2004 – “In the specific case of response time, the FAA’s needs to harmonize the occupant protection requirements of its various regulations with the Orders under which the air traffic control system is operated. This lack of internal coordination has created a system where response time cannot be objectively measured prior to the point of confirmed receipt at the responder's location.” -p.64
Page 5, Review Historical Basis
ARAC 2004 – “Response Time means the measurement of time for a timed response drill. This period begins with the activation of the tower alarm, (tone or signal), followed by response information. This period ends with the initial discharge of agent upon arrival of the first ARFF vehicle(s). Elapsed time is measured from Alert Tone to Initial Discharge.” - p.65
Page 5, Review Historical Basis
ARAC 2004 – “The ARFFRWG concluded that, for the purposes of accountability as opposed to evaluation, it is inappropriate to mandate a specific response time applicable to ARFF personnel responding to an actual emergency within the regulation itself.” - p.69
Page 5, Review Historical Basis
ARAC 2004 –
(i) For the purposes of timed response drills, within 3 minutes from the time of the alarm, at least one required airport rescue and fire fighting vehicle shall reach the furthest end of the farthest usable runway serving air carrier aircraft from its assigned post and begin application of the required extinguishing agent. – p.104
Page 5, Review Historical Basis
CFR, FAR Part 139.319
(i) Within 3 minutes from the time of the alarm, at least one required aircraft rescue and firefighting vehicle must reach the midpoint of the farthest runway serving air carrier aircraft from its assigned post or reach any other specified point of comparable distance on the movement area that is available to air carriers, and begin application of extinguishing agent.
Page 5, Review Historical Basis
ICAO Annex 14Response time9.2.23 The operational objective of the rescue and fire fighting service shall be to achieve a response time not exceeding three minutes to any point of each operational runway, in optimum visibility and surface conditions. - p.9-6
Page 5, Review Historical Basis
NFPA 403-2009
B.5.1 Quantity Q1
where:PCA = practical critical area
R = rate of application T = time of application (1- min.)
Page 7, Response Time Not Part of Q1 Equation
DOT/FAA/AR-11/29
“The ARFF response time directly relates to occupant survivability, so it has been included in this assessment.”
-pg.4
DOT/FAA/AR-11/29
“The rationale from the RFFP and the commentary from NFPA 403 Annex B [1] are vague on explicitly establishing the link between the response time of vehicles, the control of the exterior fuel fire, and the onset of hazardous conditions to occupants. This relationship can quantitatively be expressed as TV + TE ≤TB (5a) TV = vehicle response time TE = time to extinguish exterior pool fire threat (90% control) TB = time occupants are exposed to life threatening conditions By establishing this metric, performance measures can be assessed.”
-pg. 13
DOT/FAA/AR-11/29
“The vehicle response time aspects described here and in section 3.6.2, are revisited in the current threat analysis, section 5.2.3. As a means of describing the historical basis of protection criteria, a return to the Lindemann approach [17] is sufficient, where 3 minutes is stated as the time when occupants will be exposed to threatening conditions for an unabated fire. If the ARFF resources arrive at the scene within 2 minutes, fire control must be achieved in 1 minute. Thus, equation (5a) is met.” TV (2 min) + Te (1 min) ≤TB (3 min) -p. 13
DOT/FAA/AR-11/29
“It is difficult to establish the quantitative basis of the current approach on a step-by-step basis from the literature. A simple summary has been provided by Tom Lindemann, a past member of the NFPA 403 Technical Committee [17], which states that FAA research indicates that when an aircraft is involved in a fuel spill fire, the aluminum skin will burn through in about 1 minute…Therefore, ARFF personnel and equipment must reach the scene in 2 minutes to meet the anticipated Burnthrough scenario.” -p. 104/105
Page 4, Approach
Airport Accident Review?
• No specific aircraft accident report(s) identified (occurring in the RRA) w/caveats to justify an argument that an ARFF response time >2-min. but <3-min. contributed to additional injuries/fatalities.
Page 15 & 26 Performance Criteria (Caveats)?
• Intact fuselage• If fire immediately
”immerses” aircraft, ARFF may be ineffective,
– Even with quick (2 min) response
DOT/FAA/AR-11/29
“There is no method to predict whether a fire will be located in close proximity to the aircraft, whether the fire will occur on just one side, or whether the aircraft fuselage will be immersed in fire.”
-p.69
DOT/FAA/AR-11/29
“It was found that a heat flux of 9.59 kW/m² was the threshold value for causing the aircraft interior to ignite. “ - p.72Scenario 1
• Aircraft skin thickness - 0.5 (0.02) mm (in.)
• No wind “A worst-case (very thin) fuselage thickness was assumed (0.02 in.)” - p.70
DOT/FAA/AR-11/29
“Ignition of the aircraft interior was established as a performance threshold because flashover conditions can develop within 60 seconds after interior ignition. This is consistent with observations from aircraft incidents and fuselage tests as well as with data obtained from interior fire spreading in passenger rail cars.” - p.71
• With caveats?
Page 19, Chart is Arbitrary
DOT-FAA-AR-11-29
“Not all interior ignition scenarios result in rapid development of flashover conditions…” -p. 71
• No specific accident report(s) identified where interior flashover occurred from fuselage burn through w/caveats (in the RRA) that contributed to any fatalities.
DOT-FAA-AR-11-29
“The fire was assumed to be equal to the airplane length and to extend indefinitely perpendicular to the airplane fuselage.” -p.71
• When and where has this ever occurred?
A Hypothetical Argument w/Caveats Is Not Conducive to Objective Risk Analysis
2-Minute Response is Ignorant of NFPA 1710 -
Cascade of Events
