GA Update June 2021

GPS APPROACHES

On June 25th the UK’s use of EGNOS comes to an end, here’s what it all means

You’ve probably heard of ‘GPS approaches’, technically known as RNP approaches in the UK, even if you haven’t flown one, but at the end of this month — June 25th to be precise — they’ll be changing in the UK for the time

being. That’s because the UK has decided not to continue with membership of the European Galileo and EGNOS programmes following the UK’s decision to leave the European Union.

While most aircraft use the U.S. worldwide satellite system for general navigation, for it to be precise enough for an ‘instrument-type’ approach it needs a bit of a boost which is where EGNOS (the European Geostationary Navigation Overlay Service) in Europe and WAAS (the Wide Area Augmentation System) in the U.S. come in.

These two Space Based Augmentation Systems (SBAS) and others around the world provide corrections to give even better lateral and vertical position accuracy — less than three metres — for safety-critical applications such as instrument approach procedures to lower minima.

It’s this increased accuracy, particularly vertically, that’s

facilitated some ‘GPS approaches’, or more accurately LPV, in the UK in the last few years.

LPV stands for Localiser Performance with Vertical guidance. The important word here is vertical, which means that properly equipped aircraft can use ‘GPS procedures’ for an approach to suitably equipped runways with minima similar to a Category 1 Instrument Landing System (ILS).

In practice that means aircraft using approved onboard equipment, rather than ground-based navigation aids such as an ILS, can descend to 200ft on the approach before deciding whether to continue to land or go-around. Without it the Minimum Descent Height tends to be 400ft or higher.

Without the use of the European ‘augmentation system’, and in close co-ordination with the affected aerodromes, NOTAMs are being issued to notify pilots that LPV lines of minima on the RNP IAPs are not available for use from the 25 June 2021 until further notice.

As a result, pilots will need to make use of the other elements of the RNP instrument approaches, LNAV and LNAV/VNAV(BaroVNAV)

HOW THINGS ARE CHANGING

or alternative instrument approach procedures where available, and plan flights taking account of the loss of LPV operating minima at affected airfields.

That said, Crown Dependency aerodromes such as Jersey, Guernsey and Alderney have separate arrangements for access to EGNOS and will retain their LPV procedures after June 25.

There are two EGNOS Ranging and Integrity Monitoring Stations (RIMS) in the UK and they will continue to operate; it’s also expected that the signal-in-space will remain unchanged after 25 June 2021. So, provided that the received signal is still indicating adequate integrity, pilots won’t be required to de-select the EGNOS signal from their GPS and the service can still be used in other flight phases.

UNTANGLING ‘RNP APPROACHES’‘RNP approach’ is really a catch-all name for a number of types of approach. To really understand them it’s first worth reviewing the difference between Precision and Non-Precision Approaches.

Traditionally, a Precision Approach, such as an Instrument Landing System (ILS), provides lateral and vertical guidance for a stabilised continuous descent, whereas

a Non-Precision Approach (NPA) is based on conventional navigation aids such as an NDB, VOR and DME and provides lateral guidance only to bring the aircraft to a point where the runway is in view for a visual landing. So, ’RNP approaches’ can provide both ‘non-precision’ (LNAV) approaches and approaches with vertical guidance (LPV and LNAV/VNAV) similar to those used on Precision Approaches.

‘RNP approaches’ come under the heading of Performance Based Navigation (PBN) which is becoming more established worldwide. It includes (standby for a load of acronyms…) approaches called RNP APCH and RNP AR APCH. In reality all of that’s much less complex than it sounds — RNP stands for Required Navigation Performance, while APCH is simply an abbreviation for Approach and AR for Authorisation Required.

Essentially, then, RNP and RNP AR procedures allow pilots to use very accurate onboard navigation kit for approaches instead of traditional ground-based external guidance aids. In some circumstances they also allow the replacement of visual and circling approaches by instrument approaches.

So put simply, RNP and RNP AR

procedures can provide a lateral and vertical GPS path for pilots to fly to a decision height of 200ft from which the decision to continue the approach can be made.

The end of the EGNOS agreement in the UK will only impact the LPV elements of an RNP APCH (Instrument Approach Procedures) IAPs approach, so only the LPV line of minima will be NOTAM’d as unavailable, before being withdrawn. LNAV (Lateral Navigation only) and LNAV/ VNAV (Lateral and Barometric VNAV) lines of minima published on RNP APCH will continue to be available.

To use ‘RNP approaches’ aircraft need to have a suitable IFR approved GNSS set-up installed. The equipment must also contain an up-to-date navigation database with details for the required ‘RNP approach procedure’ to an airfield. When activated, the aircraft navigation equipment automatically sequences through the procedure’s legs to bring the aircraft to the runway.

There must also be an On Board Performance and Alerting system to warn the pilot of positioning errors, loss of signal, degraded tracking accuracy and other parameters.

GPS APPROACHES

GPS augmentation around the world

© EUSPA

GPS APPROACHES

So how do they work in practice? RNP and RNP AR approaches use a series of waypoints, legs, speed and altitude limits stored in the navigation database to provide both a lateral and, crucially, a vertical trajectory.

The main difference from, say, an ILS is that rather than requiring costly ground facilities for the approach they use the aircraft’s onboard navigation performance capability. An aircraft tracking the final approach course with a centred needle can be expected to be within 0.3 nm of the centreline 95 percent of the time.

Most ‘RNP approaches’ in the UK will be set up to give a 10nm track to the runway threshold. Depending on the design of the approach, the 10nm ‘waypoint’ might beknown as the “initial fix” (IF) or the “intermediate fix” (IAF). Where this point is the intermediate fix there will be other legs leading to this point, the start of which will be the Initial Fix.

The Final Approach Fix (FAF), is usually set at around 5nm from the runway threshold. From the FAF a descent profile will be defined with a range/altitude countdown, usually at 1nm intervals to the missed

approach waypoint (mapt WP). The angle of descent varies slightly from airfield to airfield but is usually 3 to 3.5 degrees.

In practice, whichever type of ‘RNP approach’ you fly depends on the equipment in the aircraft. Some early model GNSS receivers allow lateral guidance only (LNAV) approaches, while later models might incorporate WAAS in the U.S. or EGNOS in Europe to allow vertical guidance as well.

For pilots flying near to airfields, especially those outside controlled airspace which have published RNP procedures, it’s worth noting that aircraft flying these procedures could be up to 15nm from the airfield, so consideration must be given to maintaining suitable vertical and lateral separation from an aircraft on an ‘RNP approach’.

So, while the primary purpose of the EGNOS service has been to increase precision flight, especially in marginal weather conditions and to lower flight decision minima, a range of alternate satellite based and instrument approach navigational aids will remain available to flight crews and aerodromes that continue to be safety approved, including Area Navigation (RNAV) Non-Precision Approaches and Instrument Landing Systems (ILS) Precision Approaches, respectively.

084°086°086°084°13001300(1280)(1280)1300(1280)

RW09RW09RW09PB09F

2100(2080)TISEV

2100(2080)

300300

300

300

600

600

300

300

600

262°

LHA 21001 MIN

354°

174°4.5 5.0

4.9

4.06.4

5.2

4.9

3.9

2100

ELPAPIAF

PB09FFAF

PBM01

PBM02PBM03

2100

OKDETIAF

2100

TISEVIAF/IF

RW09MAPt

SBH

082°

10NM

578

650

962

952

912

358

084°

084°

264°

174°

355°

984(964)

654(634)

373(353)

271(251)303303(283)(283)303(283)

199199(179)(179)199(179)

408(388)

10771077(1057)(1057)1077(1057)

720(700)

MAX 185KIAS forMissed Approach.

MAX 210KIAS for CAT C Procedure and Holding.

25NM

FRO

M TISEV

10NM

25NM FROM ELPAPTAA2100

TAA2400

(TISEV)

(TISEV)

(ELPAP)

TAA2100

25NM FRO

M O

KDETTAA

2100

(TISEV)

(OKDET)

6000N 6000N

001 30W 001 00W

001 30W 001 00W

NM to RW09 6 5 4 3 2 1 ALT(HGT) 1970(1950) 1650(1630) 1330(1310) 1020(1000) 700(680) 380(360)

Rate ofdescent

G/S KT 160 140 120 100 80 FT/MIN 850 740 640 530 420

RECOMMENDED PROFILE LPV - VERTICAL PATH ANGLE 3.0° (LNAV 5.24%), 318FT /NM

NOTE Reduced VM(C) minima applies to aircraft which manoeuvre outside the quadrant north of RWY 09/27 C/L and west of RWY 15/33 C/L.

AERO INFO DATE 15 FEB 21

SUMBURGHRNP

RWY 09(ACFT CAT A,B,C)

INSTRUMENT APPROACH CHART - ICAO

CHANGE (5/21): MAG VAR. MAG TRACKS. RAD REQUENCY.

6.410.4 0NM

24

21090°

180°

A B C 320(300) 320(300) 340(320) 630(610) 630(610) 630(610) 800(779) 1200(1179) 1400(1379)

800(779) 800(779) 1130(1109)

OCA(OCH)

Aircraft Category LPV LNAV Total Area Restricted (See Note 1)

VM(C)OCA(OCH AAL)

NAnnual Rate

of Change 0.24°E

VAR 0.9°W

- 2022

TWR 118.255 SUMBURGH TOWERRAD 131.300, 123.155 SUMBURGH RADARATIS 125.855 SUMBURGH INFORMATIONAFIS 118.255 SUMBURGH INFORMATION

AD ELEVATION 21THR ELEVATION 20

BEARINGS ARE MAGNETIC

OBSTACLE ELEVATION1077 (1057)

AMSL(ABOVE THR)

MSA 25NM ARP

MAPt (LNAV): RW09Continuous climb to 3000. Initially straight ahead to PBM01, thenturn right to PBM02, right toPBM03 and right to SBH to jointhe hold or as directed.

WARNINGFinal and missed approach areas of the procedure lie in the vicinity of high terrain and obstacles. Do not descend below procedure MNM ALT/HGT.

TRANSITION ALTITUDE 6000EGNOS CH 45339 E09A

WAYPOINTSOKDET : 594710.81N 0013753.86W ELPAP : 595533.08N 0013948.23WTISEV : 595140.13N 0013855.03W PB09F : 595207.44N 0013057.11WRW09 : 595250.97N 0011819.03W PBM01 : 595325.50N 0010803.67W PBM02 : 594834.11N 0010658.33WPBM03 : 594800.87N 0011636.63WSBH : 595256.55N 0011741.40W

TCH 40

RNP APCH

AD 2-EGPB-8-2

350350

650650

350

350

350350

350

350

350

350

650

650

350

350

650

650

11101110(1023)(1023)

18001800(1713)(1713)265°

NIRMO2500(2413)

BJ27F2000(1913)

RW27RW27RW27

265°

1110(1023)

1800(1713)

NDB(L) GST

091°

271°LHA LHA 250025001 MIN1 MIN

LHA 25001 MIN

FAIRFORDFAIRFORD

R1552000SFC

R2042200SFC

GST 331 gst

515331N 0021004W

ASTONDOWN

SOUTHSOUTHCERNEYCERNEY

SOUTHCERNEY FAIRFORD

NYMPSFIELDNYMPSFIELDNYMPSFIELD

ULLENWOOD

CHELTENHAM

STRENSHAM

NIRMOIAF/IF

10NM

937

971

650

393(306)

1261(1174)

978

666

1046

951

981(894)

1095(1008)

981

4000I-GOS 109.95D

(Ch 36Y) igos

515332N 0021005W111'

265°265°265°

265°265°265°

175°

355°355°355°

5.0

5.0

5.05.0

NIRMOIAF/IF

LAPKUIAF

3NM3NM3NMRW27MAPT

BJ27FFAF

2500

2500

2500

REKLOREKLOIAFIAFREKLOIAF

1021(934)

1145(1058)

806(719)

277(190)

368(281)

1217(1130)

434(347)

377(290)

901(814)

2255NNMM FFRROOMM RREEKKLLOO

(REKLO)(REKLO)(NIRMO)(NIRMO)

25NM FROM REKLO

(REKLO)(NIRMO)

TAA2500

25NM FROM NIRMO

(NIRMO)

TAA2500

25NM

FRO

M LAPKU

TAA2500

(LAPKU)(NIRMO)

558(471)

VAR 0.9°W

- 2019VAR

0.9°W - 2019

NNAnnual RateAnnual Rate

of Change 0.15°Eof Change 0.15°E

5200N

5200N

002 30W002 30W002 30W 002 00W002 00W002 00W

002 30W002 30W002 30W 002 00W002 00W002 00W

Rate ofdescent

G/S KT 160 140 120 100 80 FT/MIN 990 870 750 620 500

TRANSITION ALTITUDE3000

NOTES 1 Missed Approach Procedure not available without NDB(L) GST. 2 Missed Approach Procedure shall be converted to a conventional Missed Approach upon reaching 1500. 3 No Missed Approach turns permitted prior to MAPt.

MAPt (LNAV): RWY27Continuous climb to 2800, initially straight ahead to 1500 then turn right to NDB(L) GST at 2800 or as directed. (See Note 1 and 2).

AERO INFO DATE 08 JUN 20

GLOUCESTERSHIRERNP

RWY 27(ACFT CAT A,B,C)

INSTRUMENT APPROACH CHART - ICAO

CHANGE (11/20): RNP REFERENCES ADDED. BJ27F PROFILE HEIGHT REFERENCE. MAP TEXT.

MSA 25NM ARP

WAYPOINTSREKLO : 514946.46N 0015243.99WLAPKU : 515942.11N 0015429.46WNIRMO : 515444.29N 0015336.63WBJ27F : 515412.56N 0020138.31WRW27 : 515340.21N 0020939.54W

53 100

A B C

600(513) 600(513) 600(513)

1000(899) 1000(899) 1500(1399)

830(729) 830(729)

ProcedureOCA(OCH)

Aircraft Category

LNAV

Total Area North of RWY 04/22 and 09/27

VM(C)OCA(OCH AAL)

MAX 185KIASwhen flying right base

procedure (LAPKU)between NIRMO (IF)

to BJ27F (FAF)

NAnnual Rate

of Change 0.15°E

VAR 0.9°W

- 2019

APP 128.555 GLOSTER APPROACHTWR 122.905 GLOSTER TOWERRAD 128.555, 120.980 GLOSTER RADARATIS 127.480 GLOSTER INFORMATION

AD ELEVATION 101THR ELEVATION 87OBSTACLE ELEVATION

1261(1174)

AMSL(ABOVE THR)

BEARINGS ARE MAGNETIC

28

RECOMMENDED PROFILE Gradient 6.13%, 373FT/NM NM to RW27 5 4 3 (SDF) 2 1 ALT(HGT) 2000(1913) 1620(1533) 1250(1163) 880(793) 510(423)

AD 2-EGBJ-8-7

RNP APCH

SEVERNSEP - APR

4000SFC

FAIRFORDFAIRFORDMATZMATZ**

10971097(1010)(1010)

BRIZE NORTONBRIZE NORTONCTR DCTR D35003500SFCSFC

DeffordDefford30003000SFCSFC

239(152) 642

(555)

350(263)

256(169)

326(239)

Defford3000SFC

SEVERNSEP - APR

4000SFC

BRIZE NORTONCTR D3500SFC

OXF

ORD

AIA

A50

00SF

C

FAIRFORDMATZ*

1097(1010)

349(262)

353(266)