Unit -4

Airport Engineering

Q1)          The basic runway length of the given airport is 2000m. The elevation of the airport site is 300m above MSL and reference temperature is 33.35°C. Calculate the corrected runway length?

Ans 1): Elevation correction = 7% per 300m rise in elevation

=

                                            = 140m

Therefore corrected runway length = 2000+140 = 2140m

Temperature Correction = 1% for every 1°C rise in temperature

Rise in temperature = 33.35-13.05

        = 20.3°C

Therefore, Temperature correction =

       = 432.42m

Hence, Corrected runway length = 2140+432.42 = 2574.42m

Q2)          An aircraft approaches the threshold of runway strip at a speed of 240kmph. The pilot decelerates the aircraft at 1.436m/s2 and takes 26 s to exit the runway strip. If deceleration after exiting the runway is 0.9m/s2, then find the distance of the gate position from the location of exit on the runway?

Ans 2):

Now, after exiting runway

Here, v = 0

u=29.334m/s

Therefore, distance till stopping

Q3)          State the aircraft characteristics?

Ans 3): Aircraft characteristics are of prime importance to the airport planner and designer. The following characteristics need to be studied;

• Type of Propulsion
• Size of Aircraft
• Minimum Turning Radius
• Minimum Circling Radius
• Speed of Aircraft
• Capacity of Aircraft
• Aircraft weight & wheel configuration
• Jet Blast
• Fuel Spillage
• Noise

Q4)          What do you understand by Minimum Turning Radius?

Ans 4): Minimum Turning Radius

• In order to decide the radius of taxiways, the position of aircrafts in loading aprons & hangars and to establish the path of the movement of aircraft, it is very essential to study the geometry of the tuning movement of aircraft.
• To determine the turning radius, a line is drawn through the axis of the nose gear when it is at its maximum angle of rotation. The point, where the line intersects another line drawn through the axis of the two main, gears, is called the centre of rotation.

Q5)     What do you understand by Minimum Circling Radius?

Ans 5): Minimum Circling Radius

• There is certain minimum radius with which the aircraft can take turn in space. This radius depends upon the type of aircraft air traffic volume and weather conditions. The radii recommended for different types of aircrafts are as follows;

1. Small general aviation aircraft’s under UFR conditions, 1.6km.
2. Bigger aircrafts, say two piston engine under VFR conditions = 32km
3. Piston engine aircrafts under IFR conditions = 13km
4. Jet engine aircrafts under IFR conditions = 80km

• The two nearby airports should be separated from each other by an adequate distance so that the aircrafts simultaneously landing on them do not interfere with each other. If the desirable spacing between the airports cannot be provided, the landing and take-off aircrafts in each airport will have to be timed so as to avoid collision.

Q6)          What do you understand by Jet Blast?

Ans 6): At relatively high velocities, the aircrafts eject hot exhaust gases; the velocity of jet blast may be as high as 300kmph. This high velocity cause inconvenience to the passengers travelling in the aircraft. Several types of blast fences or jet blast deflector are available to serve as an effective measure of diverting the smoke ejected by the engine to avoid the inconvenience to the passengers. Since, the bituminous (flexible) pavements are affected by the jet bust, therefore, it is desirable to provide cement concrete pavement at least at the touch down portion to resist the effect of the blast in preference to the bituminous pavements. The effect of jet blast should also be considered for determining the position, size and location of gates.

Q7)          Explain the general points to be observed during Airport Grading?

Ans 7): The following general points are observed in the grading-

1. The amount of cut and fill should, as far as possible balance each other. The haulage distance and the amount of earthwork to be moved should also be kept to a minimum.
2. Sub-grade soils should, as far as practicable, be of a uniform character to ensure a uniform sub-grade support.
3. Proper surface and subsurface drainage should be done to ensure the stability of the pavements and the embankments.
4. Grading plans should be prepared to carry the surface water away from the runways, taxiway, apron areas and building areas.
5. If two or more landing strips cross each other, the intersecting runways are assigned common grade elevation at the intersection.
6. The areas at the ends of the landing strips should also be graded as a precautionary measure. Thus the aircraft, which may enter these areas unintentionally due to premature take-off a due to undershooting, the strips while landing would have minimum.
7. The choice of the equipment for clearing grading and compacting should be determined considering the nature of the material involved job size, local practice and construction time assigned etc.

Q8)          Explain Class A and Class B messages?

Ans 8): Class A Messages: Message essential to countries and to airline operating agencies or the safety and the regularity of international air services are known as Class A Messages. The message comprises of;

1. Distress message
2. Messages for the safety of human life and urgency message
3. Flight safety message
4. Meteorological message
5. Flight regularity message
6. Notices to airmen
7. Service message

Class B Messages: Message essential airline operating of international air services are known as Class B Messages. The message consists of;

1. Reservation message
2. General airline operating agency message

Q9)          What are the general considerations suitable for site selection of a helipad?

Ans 9): The general considerations in the choice of a suitable site for a helipad are;

1. It should be located in close proximity to the traffic generating area.
2. It should have a convenient access by ground transportation, e.g. Roadway or railway.
3. The ambient noise level should be considered.
4. The site for a helipad should provide unobstructed approach departure paths for helicopters.

Q10)      Calculate the airport reference temperature when the monthly daily temperature and monthly mean of average daily temperature of the hottest month of the year are 49°C and 40°C respectively?

Ans 10): Airport Reference Temperature;