GEOMETRIC DESIGN OF AIRPORTS(2)

CVLE 535AIRPORT ENGINEERING

Dr. Youssef Attallah

Aircraft Manoeuvring Principles

Aircraft use tricycle landing gear configurations

Special manoeuvring requirements need to be accounted for Tricycle gears are less stable than four

wheelers Tricycle gears permit tighter manoeuvres

Always consult with the aircraft manufacturer documents for airport design

Sample Aircraft Manoeuvring EnvelopesBoeing MODEL 777-200LR, 777F

Steering angle= angle defined by the aircraft longitudinal axis and the nose gear (usually up to 70 degrees for some aircraft)

Few Definitions

Turning Center= the imaginary point where the aircraft pivots while turning at a given steering angle.

Turning center

Sample Aircraft Manoeuvring (B777-300)

While steering angles as high as 60-70 degrees are technically possible in some aircraft, it is unwise to ask pilots to use such high steering angles in practice while on a taxiway

Very high steering angles are typically associated with apron manoeuvring (while aircraft is moving at very low speeds)

Consider the pilot visibility when designing your airport infrastructure. Aircraft have limited frontal and lateral visibilities

Consult the appropriate aircraft manuals when in doubt

Operational Issues

Sample Aircraft Forward Visibility

Apron design requirementsTaxiway design requirementsTaxilane design requirementsRunway exit design requirementsHolding bay design

Implications of Aircraft

Manoeuvring

Taxiway Design Standards and Requirements

Source: FAA AC 5300-13 (Chapter 4)

Dictated by safety analysesProvide sufficient taxiway and runway-

taxiway intersection width to avoid accidents (i.e., landing gears go into the shoulder or grass)

Use simple FAA criteria to design taxiway-taxiway or taxiway-runway intersections

Where is the Info. in FAA AC 150/5300-13 ??

Taxiway Dimensional Standards (per FAA)

Why Do We Need Taxiway Fillets?

Taxiway Fillet Design Rationale

Taxiway Fillet Design Solution

Critical DimensionsR - Radius of CLL - Length of filletF - Inner fillet radiusW - Width of taxiway

Taxiway Fillet Design Standards (per FAA)

According to FAA the following equivalent design procedures can be used instead of the values in the previous table

Taxiway safety area equals the aircraft wingspan

Taxiway OFA (Object Free Area) equals 1.4 times the critical aircraft wingspan + 20 ft. (6 m.)

Taxilane OFA (Object Free Area) equals 1.2 times the critical aircraft wingspan + 20 ft. (6 m.)

Taxiway Design Equivalencies

Example: Taxiway Intersection for B777-300

Look at Boeing 777-300 airport compatibility documents

Aircraft fits design group V (< 213 ft. wingspan) – 212 ft. in wingspan

31.22 m (102 ft. and 5 inches) of wheel base

10.97 m (36 ft.) of wheel track (between center of main landing gear struts)

Goal:Design a suitable taxiway-taxiway intersection for a Boeing 777-300

Boeing 777-300 (per Boeing data)

From Table 4-2 in the FAA AC 150/5300-13 obtain the following parameters:

R = 150 ft. (radius of taxiway)

L = 250 ft. (lead-in fillet)

F = 85 ft. (fillet inner radius - centerline tracking)

W = 75 ft. (taxiway width)

Use FAA Criteria for Taxiway Fillet Design

Solution Drawing

Some minor problems are identified

The aircraft has a long wheel base and thus track-in distances are excessive

According to Boeing the distance from the pavement edge to the outer wheel is 4.0 m (14 ft.)

This is below the FAA required value of 15 ft. (4.5 m.)

See the examples in the following pages

Reality Check (with Manufacturer)

Sample Solution for Boeing 777-300

Sample Solution for Boeing 777-300

Example Boeing 777-300 Taxiway-Taxiway

Recall FAA Table 4-1 (AC 150/ 5300-13)

Large paved areas to hold more than one aircraft at a time near a runway end

Provide the physical space for a runway departure queue

Provide operational flexibility to ATC personnel to sequence aircraft in a departure queue

Should be simple for pilots to use them adequately

Some busy airports use 5-6 holding bays

Holding Bays

Sample Holding Bay (Boeing 777-300)

Taxiway Fillet Design (Table 4-2)

Use detailed add-on packages to Autocad such as Autoturn software (from Transoft Solutions)

Use FAA AD42 software (approximate techniques to study aircraft kinematics on the ground)

Detailed Aircraft Trajectory Analysis

FAA AD42 Program Screens