RVSM: NIGERIA JOINS THE REST OF THE WORLD

(article written September 2008)


Nigeria successfully joined the rest of the world on the 25th of September, 2008 in implementing RVSM, in achieving this feat, an implementing office was set up in NAMA five years ago headed by a National Manager who with other members of his team mid-wife the programme.The team had personnel from relevant aviation agencies such as NCAA, NIMET, NCAT and the Nigerian Air force.

During these period seminars and training were organized to sensitize airlines and the aviation family in general.NAMA the principal agency implementing the RVSM is responsible for our compliance. They were able to sign letters of agreement between Kano Flight Information Region (FIR) and some other countries FIRs, namely Njamena, Niamey, Brazzaville, Accra e.t.c. Also over 73 Air Traffic Controllers (ATC) and 48 Aeronautical Information Services (AIS) personnel were trained and certified by the management to operate the RVSM. The training was not a NAMA affair alone as NCAA inspectors, NIMET staff, operations personnel, engineers & pilots in civil and military aviation also benefited.

Reduced Vertical Separation Minima or Minimum (RVSM) is an aviation term used to describe the reduction of the standard vertical separation required between aircraft flying at levels between FL290 (29,000 ft.) and FL410 (41,000 ft.) from 2,000 feet to 1,000 feet. The North Atlantic System Groups that implemented RVSM first determined that they were only implementing a change to one minimum from 2,000ft to 1,000ft; therefore, that minimum being singular the correct terminology is minimum not minima.


RVSM increases number of aircraft that can safely fly in a particular volume of airspace. The goal of RVSM is to reduce the vertical separation above flight level (FL) 290 from the current 2000-ft minimum to 1000-ft minimum. This will allow aircraft to safely fly more optimum profiles, gain fuel savings with its attendant cost, reduce C02 emission, greater operational flexibility for controllers and increase airspace capacity by introducing six new flight levels.


In the past, standard vertical separation was 1,000 feet from the surface to FL290, 2,000 feet from FL290 to FL410 and 4,000 feet for FL420 and above. This was because the accuracy of the pressure altimeter used in aircraft to determine level decreases with height. However over time Air data computers (ADC) combined with altimeters have become more accurate and autopilots more adept at maintaining a set level, therefore it became apparent that for newer aircraft, the 2,000 foot separation was too cautious. It was therefore proposed by ICAO that this be reduced to 1,000 feet.

RVSM was implemented between 1997 and 2005 in all of Europe, Middle East, North Africa, Southeast Asia, North America, South America, and over North Atlantic, South Atlantic, and Pacific Oceans. The North Atlantic implemented initially in March 1997 at flight levels 330 through 370. The entire western hemisphere implemented RVSM FL290-FL410 on January 20, 2005.

Not surprisingly the North Africans implemented the RVSM in 2002 with the Europeans, leaving the Sub-Saharan and India Ocean states behind, which most probably necessitated the 25th September, 2008 deadline. In joining the rest of the world, flights going east wards in the country’s airspace and within RVSM envelop will be given odd number flight levels such as 290,310,330,350,370,390 and 410 while flights going west ward will be given even number flight levels as 280,300,320,340,360,380 and 400.


Aircrafts with the required Minimum Aircraft Systems Performance Specifications (MASPS) and approved by their respective States (in Nigeria NCAA) for RVSM operations will be permitted to fly in RVSM Airspace. Non compliant aircrafts, excluding State aircraft (i.e. aircraft belonging to the customs, police, military) will be required to operate at or below FL280. The Air force and other sky gymnast should remember that Formation Flight are not allowed within the RVSM envelop.

Non-RVSM-approved aircraft intending to operate above FL 410 will be required to have the capability to execute an uninterrupted climb or descent through the RVSM airspace. Such flights shall be given appropriate ATC clearances, which will be subject to traffic levels at the time clearance is requested.

The basic components of an RVSM-compliant aircraft system involves but not limited to the pitot/static system, which includes the pitot tube/static port, standby altimeter, VSI, airspeed/Mach and associated plumbing. The ADC is the brain of the system. it is generally required that the aircraft have two primary altitude measuring system, one auto altitude control and an altitude alerting devise before entering the RVSM envelop.

Also aircraft's flight performance must be checked or confirmed by a ground based Height Monitoring Unit (HMU) or by a portable GPS Monitoring Unit, with the latter, instruments installed aboard the subject aircraft.

Also aircraft over 15000 kg or having more than 30 seats must have a collision avoidance system called ACAS II, i.e. TCAS II Version 7 as the older version are not compatible with RVSM and are susceptible to false alarm. For aircrafts manufactured before April 9 1997 they need their actuators and mechanical flight controls upgraded to maintain a precise altitude. Older actuators may not be able to maintain the necessary tolerance at altitude.

The crew operating in the RVSM envelop should endeavour to notify ATC immediately in an event of turbulence, auto altitude control failure, loss of either the altimetry system, thrust necessitating descent or any other equipment failure that will affect the ability of the aircraft in maintaining a flight level.


Challenges: the RVSM has been dogged with mid-air crisis phobia, by reducing the space between aircrafts; RVSM may increase the number of mid-air collisions and conflicts. In the last eleven years since RVSM was first implemented not one collision has been attributed to RVSM, so NAMA should ensure it shall be the same over here, like we say in Nigeria, it shall be permanent.

The aircraft manufacturers have their own challenges too, some equipment on Master Minimum Equipment List (MMEL) for the RVSM operation such as the collision warning TCAS II Version 7 and Emergency Locator Transmitters (ELT) which transmit automatically. These equipments were on Gol Airlines Flight 1907 operated by a seventeen-day old Boeing 737-800 aircraft with test, ferry and operational time of 200hrs only, on the 29th of September 2006 and carrying 154 passengers which tipped the wing of a Legacy business jet mid-air in the Brazilian air-space and headed for the Amazon jungle. It took precisely six days for the aircraft to be located. Then you wonder what happened to a brand new TCAS п and ELT, which failed woefully to notice the Lear jet and the latter refusing to transmit which is needed to speed up location and rescue.

NAMA should as a matter of urgency update their information & surveillance systems, total radar coverage programme and the automation of the flight planning system, though the management has promised to update them, we hopefully wait. They should endeavor to delicately balance and manage the different professional associations within the organization during these periods. Having successfully crossed the transition period and the critical hour which was the 24th to 25th September and the hour being 2300hrs -0100hrs, which was a big challenge with respect to aircrafts flying eastwards on flight level 310,350 and 390, they must now go further by ensuring industrial harmony, in order words the remunerations and agitations of the ATC & AIS personnel should be addressed.


ATC & AIS personnel in the industry are also challenged to effectively move seamlessly from the non-RVSM era to new RVSM era and ensure the skies remain safe, which will inadvertently aid their operational flexibility, but will advise that they strengthen NATCA by making it more professional and independent. That body should be giving a voice in the industry and reduce their over dependence on ATSSSAN.

Other challenges include refusal of some domestic pilots to go for briefing before departure, the stoic silence of NCAA on aircrafts and airlines that are not RVSM compliant, and non responsiveness of domestic operators to the “W” column when filing flight plan indicating RVSM compliance, suffice for Virgin and Arik.

RVSM is here and the envelop is only open to aircrafts and operators that are compliant with accompanying benefits, the ball is now in the court of Nigerian operators to either get into this envelop or stay in the fuel guzzling and time consuming envelop, luckily for pilots that have operated flights beyond the sub Saharan region they should endeavor to share the experience garnered in the RVSM envelop.