RUNWAYS

Runway Length Requirements

Governmental regulations Airport location Critical aircraft

Sources: http://www.faa.gov/arp/150acs.cfm?ARPnav=acs

Runway Pavement Components

Full strength (FS) Take-off & Landing

Partial strength (PS) Take-off

Clear Way (CL) Take-off

Length Conditions

Normal take-off Engine failure

Continue take-off Abort take-off

Landing

Some Terms (see fig 3-22)

Lift off distance (LOD) Threshold to wheels off the ground

D35 Threshold to aircraft 35 feet above ground

Take off distance (TOD) Runway length provided to D35 with factor of

safety applied = 1.15 D35 (for normal takeoff)

Take off roll or run (TOR) Full strength pavement; “runway”

Accelerate and stop distance (DAS) Landing distance (LD)

Relationship of Distances

35’

LOD

D35

TOD

Normal Take-Off

35’

LODN

D35,N

TODN = 1.15 D35,N

Clear Zone (CLN,max) = 0.5(TODN -1.15 LODN)

TORN = TODN – CLN = FSN

FSN

TODN

CLN

Engine Failure, Continue

35’

LODE

D35,E

TODE = D35,E (do not apply factor of safety)

CLE,max = 0.5(TODE - LODE)

TORE = TODE – CLE = FSE

FSE

TODE

CLE

Engine fails

Engine Failure, Abort

DAS

TODA = DAS

FSA

TODA

PSA

Engine fails at V=V1 Stop

V1 = speed above which you continue to take offV2 = rotation or lift off speed

Landing

SD

LD

LD = SD/0.6

LD = FSL

FSL

Stop

50’

FS = “Runway”

Runway Layout

CL CLPS PSFS = “Runway”

FL

Field Length (FL) = max {TODN,TODE, DAS, LD}

FS = max {FSN,FSE, FSL}

PS = DAS – FS PSmin = 0 ft

CL = min {FL-DAS, CLN,CLE} CLmin = 0 ft CL max= 1000 ft

PS (partial strength) = SW (stopway)

Example (1/3)

Distances for typical aircraft are as follows:

LOD: Normal 6,000 ft; Failure 7,000 ftD35: Normal 7,000 ft; Failure 8,200 ft

DAS: 7,900 ft and SD: 4,500 ft. (LD = 4500/.6=7500)

Design the runway for bi-directional operations

Example (2/3)

TODN = 1.15(7000)= 8,050 ft

CLN,max = 0.5(8050 -1.15(6000)) = 575 ft

FSN = 8050-575 = 7,475 ft

Normal take-off

TODE = 8,200 ft

CLE,max = 0.5(8200 - 7000) =600 ft

FSE = 8200- 600 = 7,600 ft

Engine failure, continue

DAS = 7,900 ft

Engine failure, abort

LD = 4500/0.60 =7,500 ft

Landing

FSL = 7,500 ft

Example (3/3)

FL = max {8050, 8200, 7900, 7500} = 8,200 ft

FS = max {7475, 7600, 7500} = 7,600 ft

PS = 7900-7600 = 300 ft

CL = min {8200-7900, 575, 600} = 300 ft

300 300300 3007600

88008200

Airport Location Adjustments

Elevation 7% per 1,000 ft Fe = 0.07 E + 1; E in 000’s

Temperature Ft =0.01[T –(15-1.981E)]+1

Grade Fg = 0.1 G +1

Reference length (LR) – LR from before LR = Actual length/(Fe Ft Fg) Or, Actual length = LR*(Fe Ft Fg)

Critical Aircraft Requirements

Runway length affects Take-off weight Landing weight

Runway lengths Take off Landing

Aircraft Weights

Operating Empty Weight (OEW) No fuel or payload

Maximum Takeoff Operating Weight (MTOW)

Maximum Landing Weight (MALW) Maximum Structural Payload

Weight (MSPW) Maximum Zero Fuel Weight

OEW+MSPW

Fuel Weight (FW)

Example (1/8)

A runway is planned for an airport at elevation 2,300 ft AMSL and average temperature of 92oF. The critical aircraft is a Boeing 737-200. Determine:

1. Runway length without weight limits

2. Weight limits for an 8,000 ft runway

Runway length without weight limits (2/8)

Source: AC 150/5325-4A

Example (3/8)

100.4

Example (4/8)

69.5

Example (5/8)

100.4

69.5

Runway 8,545 ft w/0% grade MTOW 100,400 lbs

Example (6/8)

Runway 5,650 ft w/0% grade, MLW 103,000 lbs

Example with 8000 foot R/W (7/8)

69.5

Runway 8,000 ft

MTOW97,160 lbs

Example (8/8)

Distance to fly from this airport?

MTOW 97,160 lbs

OEW 67,238 lbs

Pax+Fuel 29, 832 lbs

225 lbs/pax Fuel 15 lbs/mi

50 pax @ 1240 miles60 pax @ 1090miles75 pax @ 860 miles