Instrument Pilot Operations
For any aircraft to fly safely, a pilot should have knowledge on interpretation and operation of the aircraft instruments. In addition, the pilot should have the capability to detect related errors as well as failures of these devices. This paper addresses the instruments operated by the Pilot and how they function. Whenever a pilot knows how every instrument operates and understands when a particular instrument is faulty, he/she can securely make use of every instrument to its fullest potential (Federal Aviation, 2008).
Pitot Static system refers to a united system that uses pressure of the still air and the dynamic force as a result of the movement of the airplane through the space. These integrated pressures are used to operate the airspeed indicator, vertical speed indicator and altimeter.
Impact Pressure Chamber and Lines
In this chamber and lines, there is Pitot tube that is meant to measure the total collective pressures that are available when an airplane moves through the atmosphere. Ambient pressure, which is another name for Static pressure, is always available whether an airplane is at rest or moving; it is the locally barometric pressure. On the other hand, when an airplane is moving, dynamic pressure is created, hence can be considered as the pressure as a result of motion. A small opening in the front end of the Pitot tube facilitates the entire pressure to get into the pressure chamber. In this case, the entire pressure is composed of static pressure and dynamic pressure. Additionally, the Pitot tube has another small hole at the back chamber that allows draining of the moisture out of the system in case it rains. Both the openings are to be thoroughly checked before an aircraft takes a flight to make sure that none of them is blocked (Wyatt, 2014).
Air Speed Indicator is the other instrument whose work is to utilize the Pitot tube. The full of amount pressure is passed on to the air speed indicator from the pressure chamber of the Pitot tube through another small tube. Likewise, the static pressure is transmitted towards the opposite part of the air speed indicator whose work is to neutralize the two pressures to leave the dynamic pressure indicated on the mechanism.
The type of errors that occur in the Pitot system mostly happens within the Pitot tube that holds the whole pressure of the airflow. According to the physics’ law, the total pressure should remain constant regardless of speeding up or speeding down of the airflow around the airplane. Therefore, most frequent error associated with the Pitot -static system is as a result of obstruction of the static ports, Pitot tube or both. When the Pitot tube happens to be blocked while its drain outlet remains clear, the airspeed reads zero. Similarly, if both the drain hole and Pitot tube becomes obstructed, the airspeed display acts like the altimeter whereby it reads higher airspeeds at every increase in elevation. This kind of a situation may be very risky of not identified as soon as possible. In case the static holes become blocked while the Pitot tube is in good condition, the airspeed indicator does not work properly making the indicators to be inaccurate. Eventually the altimeter freezes where the obstruction takes place while the Vertical Speed Indicator displays zero. Another issue regarding the Pitot static system is metal fatigue that can worsen the flexibility of diaphragms. Commotion or sudden maneuvers are said to cause incorrect static pressure indications (Replogle & Wahlin, 2000).
Classification of Airspace
During early time of aviation, every airspace was uncontrolled as what is today referred to as Class G airspace. There were only few aircrafts and none had instruments required for flying in the clouds. The traffic density used to be very low even at the most busy airports and the aircrafts flew at a slow pace. Even though there were no standard for climate conditions that airplane could possibly take a flight in, it was normally agreed that if a pilot remained in clear clouds and be at about one mile visibility, he/she could observe other terrain and aircrafts early enough to evade a crash. This was referred to as ‘see and avoid’. This type of airspace laid the foundation for VFR flights, and is still significant in avoiding collisions. As time passed on, the aviation field gained more knowledge to take flights even in insignificant weather and pilots realized that since sight faded when it was dark and at a particular altitude, improved climate conditions were important to see as well as avoiding other aircrafts. This is what makes higher climate minimums during the night and at a particular altitude. Minimum sky clearance restrictions and flight visibility worked fine for a moment, however, the industry of aviation was growing and things were already changing (Haffa, 2014).
Following the arrival of less expensive gyroscopic air travel instruments, flights through clouds became promising. ‘See and avoid’ used to be useless and therefore, procedures to guarantee airplanes separation were required. This resulted to the formation of air traffic control (ATC) or Class E airplane. The government initiated an airways system where each was eight nautical miles wide and with base altitude of about 1,200 feet beyond ground level, and selected the airspace within them as restricted airspace. More severe weather limits for visual flight rules (VFR) operations were introduced for the controlled airspace to further distinguish air traffic (Wyatt, 2014). During bad climate conditions, aircrafts and pilots have to be competent and prepared for IFR flights, organize IFR flight arrangement as well as direct their positions with air traffic control. When climate conditions were good, aircraft and pilots could yet fly on instrument flight rules (IFR) plans, but it was their responsibility to see and evade other aircrafts.
Class D Airspace
This class was formally regarded as Airport Traffic Area. It was introduced due to the increase of traffic at the main airports, which brought about the need for a control tower. It has an addition of a radio communication according to the meteorological law of controlled airspace. This type of airspace is portrayed by a blue line segment. This segment acts as a sign for the primary airport and indicates existence of a controlled tower. Every pilot operating with Class D airspace was supposed to converse with the tower, despite the weather conditions. This class had similar weather minimums just like those in surface based Class E aircrafts. When departing, arriving or going through a Class D airspaces, communications had to be made when operating to or from a distant field within the airspace. In case the tower is not in operation but climate information is there, the aircraft reverts to surface based Class E.
The Class C type surrounds other full of activity airports which have radar service for departing and arriving aircrafts. This airspace class has a compulsory communication requirement and has similar weather minimums as Class C and D airspaces. Many Class C types extend from the ground too about 4,000 feet high with a round diameter of about 20 nautical miles. To operate above or inside Class C, every pilot is supposed to be having a Mode C transponder. Additionally, when operating this type of Class, two-way radio communication should be established. All aircrafts departing or returning to the satellite airport within the Class C airspace should get in touch with ATC control while entering Class C.
ATC wanted to guarantee full separation for every aircraft through compulsory communications requirement. As a result of the increase in the radar coverage as well as compulsory participation by every airliner, cloud clearance is reduced to a clear of cloud with about three miles visibility. This class is intended to assist in managing the movement of high number of aircraft traffic. This is because these airlines descend from high altitude flight levels to lower altitudes and finally the landing field itself. This Class also assists in management of their departure. Pilots have to acquire a clearance from ATC before they enter in this Class type and then maintain contact through radio communication with the ATC. In Class B aircraft, there is not instrument rating needed, pilots work under VFR so long as they stay clear of the cloud and have about three-miles of in flight visibility (Wyatt, 2014).
Since most airlines that fly higher beyond 18, 00 feet have capability of IFR, the Class A type airspace was created to manage them. Thus, Class A starts at about 18,000 feet and flies up to 60,000 feet. IFR clearance is required for every aircraft in this Class; hence, there is no VFR weather limits. Aerobatics are normally forbidden in this Class type and parachute jumps and ultra light vehicles are banned without any permission from the ATC. Class A airspace is specifically meant for airliners and jets flying over extensive distances between big cities. In this Class type every flight is controlled under the IFR, thus pilots are required to hold the instrument rating as well as be on the active IFR voyage plan (Fanjoy & Keller, 2013).
The Instrument Landing System (ILS)
Probably one of the best satisfying feelings in air travel simulation can be the skills of making an excellent landing. There are usually two forms of approaches when landing an airliner under IFR rules, these are precision and non-precision approaches. The ILS therefore, is a surveillance system and precision approach designed to offer all weather airport access as well as situational alertness for several challenging applications. ILS facilitates CAT II ILS whereby the earlier ILS equipments cannot be positioned because of limited real land or rugged terrain. Both airborne and training equipments needed for the ILS design are equal to the one for former ILS guidance system. Any airplane fixed or rotary wing equipped with ILS localizer can fly the ILS approach.
For a long time, the limits for an ILS category were one and half mile visibility with a 200 feet ceiling. However, things started changing mainly in terms of reliability, capability and accuracy of the pilot. As these transformation developed, the FAA delegated three classes of ILS approaches with effectively lower minimums. Soon after, they decided that the three categories did not fir every desired situation, thus expanded it further. There exist three types of ILS approaches, that is, CAT I to CAT III. Every category has consecutive lower minimums. The categories II and III are merely available at the landing fields where they are permitted and published. Category I has a Decision Height of 200 feet with a Runway Visual Range of about 1,400 feet ((Fanjoy & Keller, 2013).
When flying an ILS, the pilot follows two signals, that is, localizer for the lateral guidance (VHF) and glide slope for vertical guidance (UHF). If the pilot tunes the Nav receiver to localizer frequency, the second receiver, glide slope receiver is tuned automatically to its appropriate frequency
This signal provides lateral information to direct aircraft towards the centerline of a runway. Localizer is similar to VOR signal apart from the radial information it provides for just one course, the runaway. Localizer information is usually displayed on a similar indicator as the VOR information. Likewise, to track the localizer, the pilot turns to the needle just in the similar manner done with VOR navigation.
This is the sign that gives vertical control to the airplane during the ILS technique. The standard glide slope path is usually 3 degrees downhill to the approach end of a runway. The pilot is supposed to follows the path faithfully and altitude becomes precisely correct on reaching the touchdown region of the runway (Federal Aviation, 2008).
Generally, the flight instruments facilitate the airliner to be controlled with utmost performance and better safety, particularly when flying extensive distances. Manufactures give the necessary flight instruments; however, using them effectively depends on how pilots understand their operation. Therefore, it is important for pilots to become familiar with functional aspects of the pilot static system as well as associated instruments.
Fanjoy, R., & Keller, J. (2013). Flight Skill Proficiency Issues in Instrument Approach Accidents. Journal of Aviation Technology & Engineering, 3(1), 17-23
Federal Aviation (2008). Instrument Flying Handbook. United States: Sky horse Publishing Inc
Haffa, R. (2014). Joint intelligence, surveillance and reconnaissance in contested airspace. Air and space power journal, 2(1) 29-45.
Replogle, J. & Wahlin, B. (2000) Pitot-Static Tube System to measure discharge from wells. Journal of hydraulic engineering, 2(3) 335-344.
Wyatt, D. (2014). Aircraft Flight Instruments and Guidance Systems: Principles, Operations and Maintenance. United States: Routledge.