Air Traffic Control at Ronaldsway, Isle of Man
2014 Onwards
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IOM ATC History Index
ATC Operations at Ronaldsway  since my retirement in September 2014
An attempt to record some of the changes to ATC operations from then up to the present day. ATC is a constantly evolving operation with new equipment and procedures being introduced on a regular basis.  As I am no longer working there, I am using various sources to keep up with the changes.
For a detailed explanation of day to day ATC at Ronaldsway see ATC 2014

Airspace Revision - November 2014
With effect from the 13th November 2014 all class 'F' Advisory Routes within UK airspace were abolished, either completely or replaced with another category of Controlled Airspace.  Around the Isle of Man route W2D to Pole Hill (for Blackpool & Leeds), W911D to Dean Cross (for Newcastle) and W928D to BLACA (for Prestwick & Glasgow) were abolished and became Class G airspace.  Aircraft formerly using these routes now leave the air route structure as soon as they cross the Isle of Man Control Zone boundary, unless they choose a longer less direct route.  Ronaldsway Radar can provide a service until around 40 miles away and then hopefully hand the aircraft off to another agency.  In many cases Scottish Control are happy to provide a service to these aircraft, depending on controller workload.
Route W911D from IOM to BOYNE (for Dublin) changed to a class 'E' airway and was renamed Y911 with a base level of Flight Level 75, the airspace is also a Transponder Mandatory Zone (TMZ) for VFR aircraft wishing to operate within its confines.  Aircraft operating under the Visual Flight Rules can cross the airspace without a clearance so long as they have an operational Mode-S radar transponder, making them visible to ATC.
The base level of FL75 can cause some additional workload to Ronaldsway controllers, particularly when runway 08 is in use as the Manual of Air Traffic Services states that controllers should keep aircraft with Controlled Airspace if at all possible, but with a short distance to touchdown from the Control Zone boundary it is almost inevitable that pilots will request to descend below the airway to avoid additional routing and wasting fuel, the ATC service being provided to them might then change three times within around 20 miles.
Revised airspace around the Isle of Man from 13th November 2014

Changes to Ronaldsway's ATC Radio Frequencies and remote Approach Radar Radio Station - December 2014
A project that dates back to the 1990s to improve Ronaldsway's VHF radio coverage at lower levels over the north of the island became operational towards the end of 2014. Originally planned and tested with an additional transmitter/receiver station on 120.850 at Jurby, revised plans have re-located the main Approach/Radar radio station to Snaefell summit from the airfield at Ronaldsway. Due to the new location and mountain top elevation, this required alterations to the main operating frequencies for Ronaldsway to prevent interference to other aeronautical radio stations. On the 22nd September 2014 'Radar 2' frequency 118.2 MHz was permanently withdrawn from service to allow engineering work to commence for the main frequency changes. With effect from the 11th December 2014 the new operating frequencies are:
Ronaldsway Approach/Radar - 135.9 MHz
Main transmitter/receiver on Snaefell Summit, with standby at Ronaldsway
Ronaldsway Tower - 119.0 MHz
Transmitters & receivers remaining at Ronaldsway
Other (when instructed by ATC) frequencies are 120.850 and 125.3 and can be used for a second radar position or Ground Movement Control when traffic requires. The old Tower frequency of 118.9 was replaced by 119.0 and is no longer available at Ronaldsway. This change to the primary Approach and Tower frequencies was the first since they were introduced into service on the 16th January 1964.

Replacement of ATC Surveillance systems at Ronaldsway  -  2011 onwards.
A requirement that was identified around 2010 was to replace the 15 year old Watchman PSR & Cossor SSR radar systems.  The Watchman would have required extensive refurbishment to continue in operation and the Cossor Mode A/C SSR needed to be replaced by the start of 2012 to comply with requirements to operate only Mode-S systems.  The replacement systems chosen were a Selex ATCR-33S Primary Surveillance Radar to be installed at Ronaldsway with a Wide Area Multilateration Mode-S SSR system operating from multiple sites around the island.  Part of the project included a ground surveillance system showing aircraft and vehicle positions on the airfield, utilising additional local receivers.  A more conventional airport located SSR Mode S system was also considered, but the WAM system promised to greatly enhance surveillance coverage at lower levels to the north, where the hills created a 'radar shadow' for airport based systems.  Another benefit was to be the airport ground surveillance of aircraft and vehicles, particularly useful at night and in poor visibility when it can be difficult or impossible to see the airfield from the control tower.
Wide Area Multilateration (WAM)
The Wide Area Multilateration (WAM) system works utilises a very different technique to older conventional SSR systems.  Instead of having a rotating aerial interrogating the aircraft transponders and receiving replies, it has multiple sites located around the island.  There are four active transponder interrogators operating on 1030 MHz and eleven receivers on 1090 MHz, plus four 'Squitter Generator' transmitters on 1090 MHz that are used for system self checking to ensure integrity.  The interrogators and SGUs are co-located at receiver sites.  The WAM system computes aircraft positions in three dimensions (only two are used in ATC displays) by registering the Time of Arrival (TOA) of aircraft transponder replies at some or all of the multiple receiver sites.  To guarantee timing accuracy all of the sites have independent GPS receivers.  The TOAs are sent to the processor in the control tower where they are also integrated with the Primary Radar returns from the ATCR-33S radar at Ronaldsway before being displayed on the controllers Situation Displays, a newer term for what used to be known as radar displays.  There is also an option to integrate aircraft generated ADS-B position reports, a system that is likely to see much wider use in ATC over the coming years.  A further eight receivers are located around the airport to provide coverage of aircraft and vehicle movements on the airfield and a selection of vehicles that are regularly used on the manoeuvring area are fitted with transponders to show their position on a display in the Visual Control Room.
Remote Aerial Locations
Wide Area Multilateration Sites
Airport Ground Surveillance Sites
 Elements of the Ronaldsway Surveillance System
Selex ATCR-33S Radar at Ronaldsway
Selex Wide Area Multilateration Aerial
The new radar system is completely processed with no primary radar 'blips' displayed on the screen as with the older system.  Instead, different symbols are used to show the source and type of information displayed. The primary and secondary radar is combined electronically and aircraft tracks are then displayed to the controller.
A Primary Radar only contact is show as a vertical cross 
A Secondary Radar (SSR) only contact is shown as a diagonal cross  x
A combined contact (PSR & SSR) is shown as a star *
Additional information is provided to the controller based on information being downlinked from the aircraft Mode-S transponder, depending on the type of transponder fitted into the aircraft.  The most basic information displayed shows the aircraft radio callsign, either as a Flight Number for airline flights, Aircraft Registration, or Military Callsign.  This information can be stored in the transponder in the case of aircraft registration, or has to be entered by the crew before each flight in other cases.  The aircraft 'height' is downlinked and displayed either as a 'Flight Level' or an Altitude if the aircraft is below 3,000ft.
More advanced transponders also downlink 'Enhanced Parameters'.  This can include, selected level on the autopilot, aircraft indicated airspeed, actual aircraft heading and the barometric pressure set on the altimeter. These can be displayed on the controllers display as required. From the Selex Primary Radar, digitized weather returns can be overlaid on the display to plan for weather avoiding requirements by pilots.
Display Screenshots 
Selex data on the Situation Display
Mode-S two line Data Block
Mode-S three line Data Block
Primary radar returns from rain showers around the Isle of Man
Airport Ground Surveillance
Airport Surveillance Test Display
Ronaldsway Visual Control Room with poor visibility at night
System installation and introduction into service  2011 - 2017
The equipment was installed during 2011 and data was being displayed in the control tower by January 2012 but due to various unforeseen technical issues,  the project had an extended development period to try and bring it up to an acceptable performance level before it could be used by ATC.  As a result of this the Watchman radar had to be modified (in common with all existing ATC 10 Cm radar systems) to prevent interference from 4G mobile phone transmissions that were planned to operate at frequencies adjacent to those of ATC radars. The Cossor Secondary Radar System suffered a major fault and was temporarily withdrawn until a new aerial could be installed and the system returned to service.  Temporary permissions had to be obtained from the UK CAA to continue operating the Mode A/C SSR system.
The new system went 'live' on the 3rd September 2017, operating in a combined Primary Surveillance & Multilateration Secondary radar only mode.  The Ground Surveillance part of the system has so far (2023) not come into service and it seems to have been abandoned.  There are also limits to services outside controlled airspace compared to the old Watchman/SSR system, with warnings and advice on unknown traffic being limited to transponding aircraft only.

Radar Interference from Wind Farms
It is an unfortunate fact that the growing number of both onshore and offshore wind farms are causing problems to ATC radar surveillance capabilities.  Most ATC radars cancel out unwanted 'static' returns by using filters that detect the difference between stationary and moving targets.  Wind turbines, by their very nature are presented to the radar processor as moving targets and it is therefore are difficult to remove them as clutter on the display.  The older Watchman radar at Ronaldsway suffered from this from time to time, even though the nearest wind farms at the time were technically over the 'radar horizon'. 
'Anaprop' Clutter on the Watchman Radar Display
Walney Transponder Mandatory Zone (TMZ)
The problem with newer fully processed radar systems is that when sufficient levels of data processing are introduced to remove the unwanted clutter from wind farms on the display, the actual aircraft returns can also be removed.  Secondary Surveillance Radar returns should be unaffected by the wind turbines and a Transponder Mandatory Zone (TMZ) has been established over the wind farm for the benefit of Warton airfield, located near to Blackpool and operated by BAe for the production and flight testing of Typhoon and Hawk aircraft.  The TMZ only operates during Warton's notified hours of opening from Monday to Friday and any aircraft that wishes to transit through the airspace must either be fitted with a serviceable Mode-S transponder or contact Warton for a clearance to transit.  At present, Ronaldsway is having to restrict radar services offered outside controlled airspace.
Restricted Airspace in the northern Irish Sea around the Isle of Man
including the Walney Transponder Mandatory Zone (TMZ)

Rationalization of the UK Ground Navigation Aid Infrastructure  -  2014 onwards.
With a major change under way to 'Performance Based Navigation' (PBN) using GPS (backed up and checked by other systems, e.g. DME beacons) as the main navigation source for aircraft there is a program by NATS En-Route Limited to reduce the number of ground based radio aids. Around the northern Irish Sea area the VOR at Dean Cross (DCS) was withdrawn from service in December 2014, leaving the DME in operation and plans indicated that the VOR beacons at Glasgow (GOW) and Turnberry (TRN) would be removed in 2016 and Manchester (MCT) in 2017. In fact, all of these beacons remained in service as of November 2017.  As of early 2019, the Glasgow VOR has been decommissioned as an en-route aid, but remains operation with reduced protected range as an approach aid for Glasgow Airport.  Two new DME only beacons established at Dundonald (DUD - just north of Prestwick Airport) and Green Lowther (GLO - in the Scottish Borders close to the village of Wanlockhead).
The New Galloway Non Directional Beacon 'NGY' was scheduled to be withdrawn in 2016, remained in service as of November 2017, but seems to have gone by January 2020.  The VOR/DME beacons at Isle of Man (IOM), Belfast (BEL) and Wallesey (WAL) are scheduled to be replaced with new equipment.  The Isle of Man beacon was re-furbished during the summer and autumn of 2017 and was due back in service on the 15th December.  Where the VOR beacons have been removed, the Distance Measuring Equipment (DME) element usually remains, as this is an important component for area navigation systems in aircraft.  They can be used to determine an aircraft's exact position automatically by using the DME ranges from two or more beacons and this can be used to check the integrity of other navigation systems.
The 'IOM' VOR/DME beacon undergoing work in July 2017
Aerial view of the 'IOM' VOR/DME in 2018
A near vertical view of the 'IOM' VOR/DME

Changes to agreed levels for Ronaldsway traffic on Airway L10 to the south east.
'Agreed Levels' are long term arrangements between different air traffic control agencies to reduce co-ordination requirements, every flight being climbed or descended to the agreed level, usually by a certain geographical location.  The agreed levels with Scottish Control for traffic operating on airway L10 to the south east of the Isle of Man had fo a long time been set too low for many modern high performance aircraft.
The revised 'Agreed Levels' with Scottish Control on Airway L10
The previous agreed outbound level for traffic heading south east towards Liverpool was Flight Level 70 (7,000 ft) which often caused a problem with higher performance aircraft such as the FlyBe Dash8s and EasyJet Airbus's reaching it rapidly after departure from Ronaldsway, resulting in a lot of extra telephone co-ordination between Ronaldsway and Scottish Isle of Man Sector.  Also inbound aircraft were being forced to descend earlier than they would like to achieve the agreed inbound level of FL80 (8,000 ft) abeam point KELLY, 15 miles to the south east of the airport and about 20 miles from touchdown if runway 26 was in use but 40 miles from touchdown if runway 08 was in use.  Raising the inbound agreed level to FL100 (10,000 ft) allowed outbound aircraft to be climbed up to FL90 (9,000 ft) without any co-ordination between Ronaldsway and Scottish Isle of Man Sector.
Airspace changes  to the south east of the Isle of Man
Introduction of RNAV-1 routes  -  9th November 2017
 In 2016, NATS notified that there was going to be a big change in the way airspace below FL245 (24,500 ft) was to be designated.  The existing 'Airways' structure dated from the early 1950s (see ATC 1950s for more information) and in recent years the designations had been in contravention of international agreements.  With the move to more Area Navigation (RNAV) systems and the removal of many of the old radio beacons, multiple routes were being designated within the same volume of airspace.  To correct the anomalies, a rolling program of re-designation of the old Airways to Control Areas was started and the airspace to the south and east of the Isle of Man was changed in early November.  Airways L10 and L70 (amongst others not affecting Ronaldsway) have had their airspace status changed from Class A to Class C and been re-designated as the 'Holyhead Control Area'.  The rather strange and short Class E Airway 'Y911' to the southwest of the Isle of Man also becomes part of the Holyhead Control Area, but retains its Class E status.
Within this airspace there are various routes designated, including one called L10 which in fact just follows the old airway centreline.  There are also new routes to the north and south of L10, M146 which is for northwest bound traffic and Q39 for southeast bound traffic. There are yet more, but these three are the only ones affecting Ronaldsway traffic.   The reason for such a plethora of routes is that the newer ones require aircraft navigation performance to RNAV-1 (with a higher accuracy required) whereas there are still many aircraft around that can only manage RNAV-5, which has a lower accuracy requirement, ATC radar being used to ensure separation between the two classes.  Eventually it will be a requirement for all aircraft using the Controlled Airspace System to carry RNAV-1 when, presumably, the structure can be simplified.
Northern Irish Sea Airspace classes from 9/11/17
Lower Airspace ATS Routes from 9/11/17
 Normal practice is to link these routes to an airport via Standard Terminal Arrival Routes (STARs) and Standard Instrument Departures (SIDs) which are pre-programmed into most modern aircraft Flight Management Systems (FMS).   The pilot then just has to select the appropriate SID from his departure airfield, then the relevant routes until connecting with the STAR at his destination which in turn connects to the Instrument Approach Procedure for the runway in use.  At present Ronaldsway does not have STARs and SIDs, which can cause some confusion to visiting aircrew as to how they connect with the en-route structure.

Manual of Air Traffic Services Part 1
7th Edition published - Effective date 28th December 2017
The MATS Part 1 is effectively the 'bible' of Air Traffic Control in the UK (and Isle of Man) and the First Edition was published in 1974, not long after I had started my career in ATC the previous year.  Before then the publication had been known as the Manual of Air Traffic Control.  To quote from sections of the foreword of the latest version:
'The Manual of Air Traffic Services contains procedures, instructions and information, which are intended to form the basis of ATS within the UK'.
Part 1 of the Manual contains instructions that apply to all UK ATSUs and is published by the UK CAA.  Part 2 contains instructions that apply to a particular ATSU and is produced locally but are approved by the CAA.  A copy of the latest edition of Part 1 can be downloaded here.
New editions are published when there are major changes to ATC procedures and Edition 7 is mainly concerned with changes associated with the move to a Standardized European Rules of The Air (SERA).

Communications Frequency Changes  11th October 2018 
8.33 KHz separated Channels
All ATC frequencies within Europe have been gradually changing from frequencies separated by 25 Khz to a closer 8.33 KHz separation, in order to provide a much greater number of available frequencies.  Area Control was the first to implement these on a rolling program starting some years ago, with UK airfields changing during 2018.  In some cases new frequencies have been allocated, but in others the only change is to the designation of the frequencies to indicate that they are 8.33 KHz channels.  The new designators, while looking like actual frequencies, are in fact just 'Channel Designators' and are close to, but not the actual frequencies used.  Some Area Control frequencies, where multiple ground stations are using the same frequency to produce the required coverage, have remained at 25 KHz separation for the time being.
In Ronaldsway's case there are no actual changes to the frequencies, just the channel designations:
Ronaldsway Approach/Radar - 135.905  (Actual carrier frequency still 135.9 MHz)
Main transmitter/receiver on Snaefell Summit, with standby at Ronaldsway
Ronaldsway Approach/Radar (when instructed by ATC) 120.855  (Actual carrier frequency still 120.85 MHz)
Transmitter/receiver at Ronaldsway
Ronaldsway Approach/Radar (when instructed by ATC) 125.305   (Actual carrier frequency still 125.3 MHz)
Transmitter/receiver at Ronaldsway
Ronaldsway Tower - 119.005 MHz  (Actual carrier frequency still 119.0 MHz)
Transmitters & receiver at Ronaldsway
Ronaldsway ATIS  123.880  (Actual carrier frequency still 123.875 MHz)
Transmitter at Ronaldsway

Airspace Revision from 23rd May 2019
With effect from this date the upper limits of the Isle of Man Control Zone and Control Areas will be raised from Flight Level 65 to Flight Level 105.  The main benefit to Ronaldsway traffic is that it will enable airways aircraft inbound from the south east for runway 26 to be turned towards the ILS intercept point earlier, thereby reducing track miles flown and fuel burn.  There have also been some minor changes to the airspace boundaries. 

Airport reduced operating hours 2020 - 2023
The Covid 19 pandemic affected operations at Ronaldsway greatly, with the airport operating on greatly reduced hours from March 2020 and Loganair operating the only scheduled service, subsidised by the IOM Government.  The reduced hours of operation continued after personal movement restrictions on the island were lifted, enabling me to take a series of aerial photographs around the airport during April and May 2020 while it was closed.
Ronaldsway Airport Aerial Pictures
For some reason (which I won't speculate on here), the airport has struggled to recruit or train Air Traffic Controllers to replace those who have either retired or left for various reasons, resulting in limitations as to the services available at time and also affecting airport operating hours.  At the time of writing this update (September 2023) the airport is notified as having to close between 08:30 and 09:05 (local time) and again between 11:00 and 11:35.  This is to allow legally required fatigue breaks for the much reduced roster of trained controllers.  Radar services are also liable to be unavailable at times due to staff shortages, with a single controller carrying out combine Tower and Approach duties.  However it still seems to be possible to extend the evening opening time to accommodate late running airline schedules.  The published airport closing time is 20:45 (local time), but extensions up to 23:00 local time seem to be quite common.  After this time the controllers 'run out of hours' and the airport has to close.  Late evening extensions also have the potential to affect staffing levels for the following morning, the possibility being that radar services might not be available until a controller who stayed late on the previous evening had completed the minimum number of hours required between shifts.  Hopefully the situation will improve, but there is a world-wide shortage of trained controllers and it can take several years to train a new entrant controller to be fully validated on all positions.

VOR/DME Approach not availaible from August 2023
A couple of NOTAMs about this.  One is that bearings from the 'IOM' beacon between 080 and 120 degrees might fluctuate and presumambly as a result of this, the VOR/DME approach to runway 08 at Ronaldsway is withdrawn. The current NOTAMs (September 2023) for the fluctuations continues until 23rd October although the one for the approach being withdrawn is only until 24th September.  I'm guessing the the potential interferrance is being caused by this radar installation, although I would have though that the company that intstalled it would have enquired with NATS as to the suitability of the site!
'Cregneash Radar'
 All pictures on this website unless otherwise credited are  © Jon Wornham