The UK's Unrequited "Satellite of Love"...
“Satellite's Gone Up to the Skies; Things Like That Drive Me Out of My Mind”
Image: alamy.com
How many of you are old enough to remember those lyrics from “Satellite of Love”, the well-known track from Lou Reed’s early 1970s album "Transformer". A classic and iconic album, it is regularly placed in the top 50 albums of all time (for some, it was a mainstay of many teenage years)! Currently, UK aviation is in a place of unrequited love with EU satellites. What on Earth are we talking about..?
You will doubtless be aware of GPS approaches (in the UK, technically known as RNP approaches). Regrettably, last month (on 25th June to be precise), GPS approaches changed in the UK for the foreseeable future - and certainly not for the best. Why, I hear you ask? The UK has decided (in its infinite wisdom) to discontinue its membership of the European Galileo and European Geostationary Navigation Overlay Service (EGNOS) programmes following the UK’s departure from the EU.
GPS Augmentation Service Areas (Pre-BREXIT) [Image: CAA]
As many will know, EGNOS is Europe’s regional satellite-based augmentation system (SBAS) that enhances the performance of global navigation satellite systems (GNSS), such as GPS and Galileo. EGNOS has been deployed to provide safety of life navigation services to aviation, maritime and land-based users over most of continental Europe. For general navigation, most aircraft (and indeed, there rest of us ground-based mortals) use the US worldwide satellite system (i.e. GPS); however, for the precision necessary to conduct instrument approaches, GPS needs a “bit of a boost”, which is where augmentation and Europe’s EGNOS come in. EGNOS provides corrections to give even better lateral and vertical position accuracy (down to less than three metres) for safety-critical applications, such as instrument approach procedures to lower minima, navigation services to aviation, maritime and land-based users over most of Europe. There are other SBAS systems across the globe (e.g. WAAS in the US), but (obviously) these are not configured for UK users.
Revised EGNOS Service Area (Post-BREXIT) [Image: EUSPA]
So, why has the UK come out of EGNOS - or, as the graphic depicts, been carved out of EGNOS? Cited in an online article, the UK Transport Secretary, Rt Hon Grant Shapps MP, in a letter to the aviation industry earlier this year, confirmed that the UK Government could not agree terms with the EU for continuing to use EGNOS, and that “[he recognised] that it nevertheless [remained] a disappointing outcome”… Really…? One could proffer that this is a bit of an understatement - especially so, for the helicopter, HEMS and GA communities!
The Transport Secretary went on to state that “[t]he Government recognises that, after this date, airspace users will not be able to benefit from localiser performance with vertical guidance procedures and instead, where possible, rely on lateral navigation procedures. The UK Government did seek to retain the use of EGNOS and, throughout the negotiation period, we continued to discuss the matter with our European counterparts. However, after carefully considering the terms that were offered to us, including the new levels of associated costs, it was not possible to reach a satisfactory settlement with the EU in the 24 December 2020 agreement ... my officials subsequently reviewed the issue with their colleagues from across Government to consider the possibility of continuing these discussions. Unfortunately, it was accepted that for the immediate future at least, there is little prospect of renewing negotiations with the European Commission on the matter.” One could posit that an EU/EC account of part of said negotiations could be viewed as somewhat different (you be the judge…).
The Transport Secretary has confirmed that the UK Government recognises that the immediate loss of EGNOS was clearly an important issue for airspace users and that the Government had begun work on exploring alternative options for providing a commensurate navigation system, including discussions with the UK Space Agency for a dedicated UK replacement service. However, even he acknowledges that this is going to take some time and considerable investment to implement - no surprises there, then... In the interim, the UK is now the only G10 member state without an SBAS: food for thought…[1]
Clearly, the Transport Secretary is also a fan of Lou Reed’s Transformer album, another of the album’s stellar tracks, Perfect Day: at the end of the chorus … “You just keep me hanging on”, which appears to be all the Transport Secretary is offering those who had (until 25 June) benefited from the use of EGNOS.
Unfortunately, there was no means of quantifying the scale of the fiscal challenge of the post-BREXIT UK continuing to benefit from EGNOS; however, one struggles with the premise that the cost of remaining in the EGNOS consortium truly outweighed that of the UK funding, designing, launching and providing its own functional SBAS… Perhaps, the UK remaining a member of the EGNOS capability was seen as too big a post-BREXIT political compromise for the EU..? So, has the UK’s aviation community just been left to “suck it up”, as there were bigger BREXIT fish to fry? [Pun very much intended…]
So where does this leave us? SBAS-enabled (i.e. EGNOS) LPV approaches enabled aircraft using approved onboard equipment (rather than ground-based navigation aids, such as an ILS) to descend to lower procedure minima (e.g. 200ft), before deciding whether to either continue visually to land or go-around. Without EGNOS, the minimum descent heights for such procedures will increase to 400ft or higher. Whilst still beneficial during adverse weather, this can be seen as a significant penalty.
Explaining the changes and implications, the CAA released the latest in their regular ‘Clued Up’ series entitled ‘Clued Up Update: GPS Approaches’. CAA state that “NOTAMs have been 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”. Whilst CAA have rightly (yes, you read that correctly…) clarified what the loss of EGNOS means, they do not (cannot?) offer any indication of when this debacle might be resolved.
CAA have also said that they understand that the signal-in-space would still be received by avionics equipment. CAA are not expecting pilots to disable EGNOS within the equipment and indeed, on some models such an action may not be straight forward. CAA are content to let the avionics box select the highest integrity approach mode available, any approach should only be flight-planned and flown to the LNAV minima.[2] Thus, pilots will need to make use of the other elements of the RNP instrument approaches, LNAV and LNAV/VNAV(BaroVNAV) or alternative instrument approach procedures where available, and plan flights taking account of the loss of LPV operating minima at affected airfields.
So, dear reader, that is where we are today and for the foreseeable future. Disappointing does not cover it; however (and it is a big however), it is important that the drive towards GNSS implementation continues. If we just throw up our hands and say it is just not worth it, then we lose the benefits of what the system brings, even if these benefits are not as good as they could be.
For many operations, 400-500ft approach procedure minima could still deliver a significant operational advantage (particularly in the HEMS space) and enable those operations to be conducted in marginal weather conditions where that might not currently be the case. In addition, although new GNSS procedures would have to be designed to LNAV minima, such procedures can (and should) be produced with a future augmentation system in mind and be ready for when a lower LPV minima might become available again.
Ultimately, the UK aviation community must apply pressure on the UK Government to sort out this mess, either directly, through your local MPs (especially if you are in the Welwyn Hatfield constituency) or through the CAA. Another way is to ensure that GNSS implementation continues apace and that operations are ready and available for a future augmentation system, which can show that the demand will indeed be there.
We opened with lyrics from Satellite of Love and those who stayed with it (hopefully) saw the connection. In closing, and still with Lou Reed’s seminal album, the refrain at the close of the track Perfect Day offers a salutary portent for our erstwhile Transport Secretary: “You’re going to reap just what you sow " (repeat to fade)...
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