Enroute and Arrival procedure, clearance

1. Instrument Flying under IFR

There are four segments for an instrument flying under IFR and each segment has specific procedures
a) Departure
b) En route
c) Arrival
d) Approach
 
 

 

2. En route procedures

Why do we need en route?

- The objective of IFR en route flight is to navigate within the lateral limits of a designated airway at an altitude consistent with the ATC clearance
- As a pilot, we must understand and be able to use various sources when we are flying en route
 
i) En-route high altitude chart
: provide aeronautical information for en route instrument navigation at or above 18,000 feet MSL 
ii) En-route low altitude charte
: provide aeronautical information for en route instrument navigation below 18,000 feet MSL
 
1) Symbols

a) MEA (Minimum Enroute Altitude)

- Ensures a navigation signal strong enough for adequate reception by the aircraft navigation (NAV) receiver
- Obstacle clearance along the entire airway.

FlightInsight. (2021). MEA? MOCA? OROCA? IFR Altitudes Explained. https://www.flight-insight.com/post/mea-moca-oroca-ifr-altitudes-explained

How much? 
- within the limit of the airway,
- Mountainous area: 2,000 feet above the highest obstacle within a horizontal distance of 4NM from the course to be flown
- Non-mountainous area: 1,000 feet above the highest obstacle within a horizontal distance of 4NM from the course to be flown.
* MEA GAP: MEAs can be authorized with breaks in the signal coverage
 
How is it charted on the chart? eg) 9000 → 

- Arrows are used to indicate the direction.
 

b) RNAV Minimum En Route Altitude, GPS(GNSS) MEA, G-MEA// eg)4000G

- Guarantees obstacle clearance using GPS for navigation (needs alternate means of navigation)
*GPS 사용에 대해서는 GPS 이외의 다른 것들을 사용할 수 있어야 한다. 예를 들어
T route 의 경우 GPS 를 사용하는 Tango route 인데, 이 때는 GPS 를 back up 해 줄 수 있는 WAAS 가 있어야 한다. 또는 Tango route 와 VOR route 가 겹칠 경우도 마찬가지다. GPS 를 대체 할 VOR 이라는 것이 있어야 가능하다. 이런 이유로 WAAS 가 있어야 Tango route 를 사용가능하다고 하는 이유는, T-route 는 VOR airways 와 떨어져 있는 경우가 많기 때문에 GPS+ WAAS 가 되어야 가능하다고 한다.
 

FlightInsight. (2021). MEA? MOCA? OROCA? IFR Altitudes Explained. https://www.flight-insight.com/post/mea-moca-oroca-ifr-altitudes-explained

* G-MEA 의 경우 고도가 더 낮은 것은/ V airways 의 경우 VOR 신호는 바닥에서 쏘기 때문에 장애물에 걸려 수신고도가 높으나 GPS 로 신호를 받는 경우 그런 장애물이 없어 고도를 낮출 수 있다. 
 
* T route: Low altitude RVA route by using WAAS (TSO-145)
- If your aircraft is equipped with a WAAS, you can use that Tango route.
 
*WAAS: Wide-area Augmentation System
 

>MEA, G MEA, MOCA 에 대한  고도 비교

- MEA: VOR signal +  obstacle clearance 로 고도가 높다
- G MEA: GPS signal (back up with WAAS or VOR) + obstacle clearance 로 그 다음 고도
- MOCA: VOR signal (22NM) + Obstacle clearance

GNSS MEA 의 고도

This change will facilitate IFR certified GNSS equipped aircraft to fly below published MEAs, but no lower than Minimum Obstruction Clearance Altitudes, Minimum IFR Altitudes, or Minimum Vectoring Altitudes, regardless of radar coverage. This would apply to all applicable airways, rather than being limited to those published with GNSS MEA minimums
 >FAA. (2017). Clearances to GNSS Equipped Aircraft Below the MEA. https://www.faa.gov/documentLibrary/media/Notice/N_JO_7110.741_Clearances_to_GNSS_Equipped_Aircraft_Below_the_MEA.pdf