Contingency procedure in Oceanic and China

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There is a contingency procedure in DOC4444 and there is a slight difference with it for china airspace contingency procedure. 

 

SPECIAL PROCEDURES FOR IN-FLIGHT CONTINGENCIES IN OCEANIC AIRSPACE (DOC4444) 

 

CONTINGENCY PROCEDURE 

In Chapter 15 of DOC4444, a contingency procedure is outlined for cases where prior clearance cannot be obtained. If this occurs, the following measures should be implemented until a revised clearance is received:

DOC 4444 chapter 15

Initiate a turn of at least 30 degrees to the right or left, leaving the cleared track or ATS route. This action aims to establish and maintain a parallel track or ATS route, offset by 5 NM in the same direction. 

If feasible, maintain the assigned flight level until established on the 5.0 NM parallel. 

Descend below FL290 and establish a 150m (500 ft) vertical offset from the standard flight levels typically used.

 

While it is acknowledged that it's impossible to account for every contingency, it is essential to factor in the surrounding air traffic and any relevant information or circumstances perceived by the pilot. 

This general procedure is outlined for situations in which a revised clearance cannot be obtained promptly, particularly when immediate rapid descent is necessary.

 

 

WETHER DEVIATION PROCEDURES

 

there is also a weather deviation procedure If the aircraft is required to deviate from track or ATS route to avoid adverse meteorological conditions and prior clearance cannot be obtained in doc 4444. 

 

for deviations of less than 5.0 NM from the originally cleared track or ATS route, remain at a level assigned by ATC,

for deviations greater than, or equal to 5.0 NM, from the originally cleared track or ATS route, when the aircraft is approximately 5.0 NM from track, initiate a level change in accordance with Table 15-1;

 

If a weather deviation is required and the pilot is unable to obtain ATC clearance, and if the situation is urgent, as a last resort, the pilot can resort to this metho.

(bearing in mind that this may result in a potential ATC violation; in reality, no pilot would want to deviate without ATC clearance).

For an aircraft heading east that needs to veer left, descend 300ft; if it needs to turn right, climb 300ft. Conversely, for an aircraft heading west, if a left deviation is required, climb 300ft; if a right deviation is needed, descend 300ft. To simplify the recall, think of it this way: for a southbound course, climb; for a northbound course, descend.

 

 

 

CHINA CONTINGENCY PROCEDURE IN RVSM

In Chinese airspace, as in any other situation, pilots are required to obtain clearance from ATC. In the RVSM (Reduced Vertical Separation Minimum) airspace in China, pilots have the option to use the term "unable RVSM" when they need to deviate from the clearance due to severe turbulence or aircraft system failures.

contingency procedure in CHINA RVSM airspace

In the event that an aircraft requires a rapid descent and is unable to contact ATC, the deviation procedure for a level change involves making a 30-degree right turn. Subsequently, the aircraft should deviate to the right of the airway centerline by 5 NM and then initiate the climb or descent to the new level .