Landing and Takeoff safety importance
Any normal flight process consists of three parts ; going, sail, and reaching. For pilots taking off and set downing are the most of import parts of their responsibility. The fact that 12 % of all aircraft related accidents have happened during takeoff stage and this sum has remained about changeless until present twenty-four hours, shows the importance of the safety during takeoff and landing and makes this capable the Centre of attending of many research surveies. ( Srivatsan, 1986 )
Looking at accidents ‘ statistics bring up the human mistake vs. engineering treatment. An norm of 50 fatal clangs has caused by pilots mistakes which could be separated into 3 different classs ; 1.Pilot mistake 2.Weather related pilot mistake 3.Mechanical related pilot mistake. Besides mechanical failure has caused an norm of 22 fatal accidents from 1950 to 2009 ( “ Accidents Statistics, ” 2010 )
Further look intoing the accidents during takeoff and landing shows that the most common type of accident is the track overrun which normally caused by engine failure or brake malfunctioning. ( Dr. Pinder, 2003 ) Takeoff is when a really heavy burden of emphasis moving on engines, therefore the opportunity of an engine failure is really high during this procedure, hence this is a duty of the cabin crew to put the needed push high plenty to finish the takeoff successfully and besides at the same clip low plenty so that no injury threatens the engine ‘s life. Adding the conditions and runway conditions makes it really complex for the pilots to put the right informations and complete these undertakings safely. Sing the accidents that has happened late, for case Air India Express flight 812 that occurred on 22th of May 2010 ( “ Accident description, ” 2010 ) , shows that human mistakes can non be avoided and this job has non been solved yet and must be taken earnestly and this is where new engineerings come into drama. ( “ TOPMS for Large Aircrafts, ” 2010 )
Takeoff public presentation monitoring history
There have been so many different types of engineerings employed by the air power industry since the beginning of its life and this is turning mundane analogue to the growing of these engineerings themselves. ( “ TOPMS for Large Aircrafts, ” 2010 ) TOPMS is a engineering that was foremost invented in mid 1980 ‘s by Raghavachari Srivatsan. He did his doctorial thesis about the design of a Take-Off Monitoring System. ( Middleton ; David B. ( Yorktown, 1996 ) And so he continued working on this at NASA ‘s Langley research Centre. Most of the work was done in TSRV fixed-base simulator at Langley. ( Wallace, 1993 ) In 1986-1987 primary trials were held at Langley utilizing 32 pilots and the consequences showed that the pilots liked the thought but did n’t desire to look down alternatively of looking at the track to acquire the information provided by this system. Then a 2nd trial was performed utilizing 17 pilots and this clip with two shows ; one heads-down show ( HDD ) and the other wide-awake show ( HUD ) . Pilots preferred the HUD and about all of them stated that the information provided is “valuable safety information non presently available during takeoff” ( Wallace, 1993 )
In April 1988, foremost flight testing was performed at Kennedy Space Center which has a 4.6 kilometer ( 15000 pes ) track, long plenty to safely prove high velocity takeoff culls. The predicted fillet point was confirmed accurate during 80 and 100 knots rejected takeoff tallies. A sum of 6 yearss proving was performed over a 2 twelvemonth period and all of them were on dry tracks. ( Wallace, 1993 )
In October 1989 the construct was represented to makers, air hoses, and other related associates but the response was non positive. Some concerns were approximately different track conditions and variable air current conditions which were non predicted by the device. Srivatsan did more simulation surveies in 1991 and 1992 but the industry still was non interested and as the consequence the device which was developed with the potency of being installed on Boeing B-777 series, did non acquire that far and remained as a research undertaking for farther development ( Wallace, 1993.
In 1998 Dr Shane Donald Pinder took a new attack and used GPS as the solo feeling machine in his device ( S. D. Pinder, Trever G. Crowe, Peter N. Nikiforuk, 2000 ) . The device contains a GPS receiving system and a micro accountant. The micro accountant should be programmed so that it collects informations merely during takeoff and landing and non the whole flight. It can besides be programmed non to roll up the unwanted information from the GPS. The information so is recorded on a USB flash thrust and ready to be analyzed, If needed for research undertakings, or is sent to the cockpit for the human interface ( S. D. Pinder, Bristow, D.N. , Davies, T.C. , 2006 ) . Unlike Srivatsan, Dr Shane tried to maintain everything simple. He started by building a theoretical theoretical account for his device. In his theoretical account he considered drag forces moving on the aeroplane, Engines ‘ pushs, weight of the aeroplane in the way of gesture, and the syrupy clash. Then he applied the Newton ‘s 2nd jurisprudence to these equations:
a = P1 + P2 V + P3 V2
Where: a is acceleration
Pn is net forward per unit mass, and ;
V is the speed of the aeroplane.
The device measures the acceleration and velocity, and by utilizing Kalman filters method, P1, P2, and P3 could be found.
Then utilizing this equation and simple kinematic equations he was able to cipher the differential supplanting which makes the computation of projected supplanting possible by integration. ( Dr. Pinder, 2003 )
S2 – S1 = v1v2vdvP1+ P2 V +P3v2
Where: S2 is the predicted place at the mention velocity
S1 is the instantaneous place
V1 is instantaneous velocity, and ;
V2 is reference velocity
Dr. Shane tested his device on a British Aerospace Jetstream 3112, a little aeroplane with 21 seats, and the consequences showed that it is possible to foretell the place within a tolerance of 15 metres. This undertaking aims to foster look into Dr. Pinder ‘s device and formalize his consequences by making more experiments since it could be a solution to illustrations like the one below.
In 2004, a MK Airlines Limited Boeing 747 crashed to the terrain at the terminal of the Halifax International Airport. The cause of the accident was discovered to be incorrect takeoff public presentation informations computation for the weight of the aircraft and hence the accelerator scene was non set right and led to cut down power at takeoff. Human mistake was once more present in the signifier of weariness, which contributed to wrong informations computation. ( TSB, 2004 ) In current takeoff public presentation systems there is no warning if the information being used is right or incorrect and if the push is adequate, so on 29th of June 2006 an Aviation Safety Recommendation ( A06-07 ) was issued toward Transport Canada ( TC ) which recommended TC to look into the possibilities of utilizing a takeoff public presentation monitoring system to supply to the flight crew an accurate and timely information about the takeoff public presentation informations. Although TC was agreed about the construct of the TOPMS and its advantages, it stated in its response ( 20th Sep 2006 ) that since there is no certified TOPMS available at the clip TC would non see put ining the device and mentioned that in order to attest this system it needs to be able to run under all different conditions such as aircraft weight, air current, runway conditions, temperature, and many other variables. This response was assessed asunsatisfactory. Then TC decided to organize a research group and aid with the development of a Takeoff Performance Monitoring System. ( TSB, 2006 )
Global Positioning System
The planetary placement system is a satellite-based radio-navigation web that provides holes in all parts of the universe at all clip of the twenty-four hours and dark. ( Dixon, 2001 ) This was the existent design specification of the GPS back in early 1960 ‘s ; to hold planetary coverage, all conditions operation, ability to function high-dynamic platforms, and high truth. ( Kaplan, 2006 ) Its development was started at John Hopkins University and so operated by US Department of Defense. The GPS system consists of three sections ; infinite section, land control section and the user section. The infinite section consists of 24 orbiters which are oriented on 6 orbital planes, 4 orbiter each plane. The land control section proctors the wellness and safety of these orbiters. And the user section is the user receiving systems which really measure the clip taken for a signal, which been transmitted from a orbiter at a known place, to make the receiving system. Then by multiplying this clip ( t1 ) by the velocity of the signal ( v1 ) , the distance ( R1 ) between the orbiter and the receiving system could be calculated. R1 = V1t1. Hence the receiving system is on a circle with the radius R1.
Then if the receiving system has the information from two orbiters, the receiving system is on one of the intersection points of R1 and R2 circles.
By holding this distance for at least 3 orbiters can so cipher the three dimensional place of the receiving system. But the state of affairs is non ever ideal. There are several mistake beginnings available, such as clock beginning mistake which is the mistake in the clock reading of the receiving system and the orbiters. Therefore the place given by three orbiters are non really accurate. The solution is a forth orbiter.
On the above image Lashkar-e-Taiba:
Thymine: system clip at which the signal left the orbiter.
Tu: system clip at which the signal reached the user receiving system.
?t: Beginning of the orbiter clock from system clip.
tu: beginning of the receiving system clock from system clip.
Ts + ?t = Satellite clock reading at the clip that the signal left the orbiter.
Tu + tu = user receiving system clock reading at the clip the signal reached the user receiving system.
Degree centigrade: velocity of visible radiation.
Now the geometric ( true ) scope = R = C ( Tu – Thymine ) = C?t
But since normally the receiving system and orbiter ‘s clock are non synchronized and a bios mistake is normally present, the scope calculated is known as pseudorange ( ? )
? = C [ ( Tu + tu ) – ( Ts + ?t ) ]
? = R + C ( tu – ?t )
Therefore ? – C ( tu – ?t ) = R and from the below diagram R = ( s – U )
?t is non unknown since it is being monitored all the clip by the land control section and right values transmits to the orbiters.
So ? – Ctu = ( s – U ) e ? = ( s – U ) + Ctu
Now to find the three dimensional place of a receiving system and the beginning clip tu information from 4 orbiters are required which lead to 4 equations:
? = x-x 2+ y-y 2+ z-z 2 + Ctu
? = x-x 2+ y-y 2+ z-z 2 + Ctu
? = x-x 2+ y-y 2+ z-z 2 + Ctu
? = x-x 2+ y-y 2+ z-z 2 + Ctu
This could be solved by one of the methods below:
- Closed-form solution
- Iterative techniques based on linearization
- Kalman Filtering
GPS can besides find the speed of the receiving system. Older receiving systems computed the speed by distinguishing the place of the receiving system which is non really accurate because there are mistakes generated by distinguishing and besides the velocity of the receiving system is non changeless. ( Kaplan, 2006 ) In modern GPS receivers the speed is determined by mensurating the Doppler displacement of the familial signal. ( Dr. Pinder, 2003 ) Doppler displacement is really frequency displacement due to the alteration of comparative velocity between the receiving system and the orbiter. ( Guochang Xu, 2007 )
GPS Error Beginnings
Free negatrons are present in ionosphere medium and these negatrons affect the GPS signals. The velocity in which the signals travel is assumed to be changeless, but the velocity of visible radiation is non changeless when specially go throughing the ionosphere medium and this could bring forth place mistakes more than 20 metres. However ionosphere is a diffusing medium, this means the ionospheric consequence depends on frequence, and therefore utilizing several different frequences could mensurate and extinguish this mistake. There are methods to get the better of this job such as double-frequency and triple-frequency combination methods. ( Guochang Xu, 2007 )
Troposphere is below Ionosphere and unlike Ionosphere it is a non-dispersive medium, this means the consequence is true for any frequence used to convey the signals. This could do more than a few metres place mistake. Tropospheric consequence depends on temperature, force per unit area, and humidness. There are several theoretical accounts generated to foretell and rectify this mistake such as Modified Saastamoinen Tropospheric Model, Modified Hopfield Model, Davis Model, etc. ( Guochang Xu, 2007 )
Multipath mistake occurs when a receiving system receives a signal than been reflected multiple times before making the receiving system. The receiving system thinks the signal was received straight and therefore the receiver-to-satellite distance was calculated incorrect. However the airdrome ‘s track environment is non a multipath environment because the edifices are non near to tracks and a clear position of the sky is ever available. ( Dr. Pinder, 2003 )
Other mistake beginnings
There are some other beginnings of inaccuracy such as clock mistake, relativistic consequence, Earth tide and ocean burden tide, hardware prejudice mistake, etc. which are comparatively bias mistakes that are extremely quotable and do n’t hold noticeable effects on the truth of this undertaking. Besides utilizing differential GPS ( DGPS ) could cut down all mistakes except for multipath consequence and receiving system noise. ( Dr. Pinder, 2003 )
With a normal GPS receiving system an truth of about 10 metres is possible but in some applications more truth is required. DGPS is a manner of bettering this truth. In this method one or more stationary GPS receiving systems, at known locations, are used to pass on with the orbiters and the nomadic receiving systems every bit good. Therefore rectification messages could be transmitted to the nomadic receiving system and a really accurate place lock could be achieved. ( Kaplan, 2006 ) In fact, in the instance of this undertaking where multipath mistake is non affectional, an truth of less than 1 metre is achievable. ( Dr. Pinder, 2003 )