This is the first skydiving report that CHIRP has received so, for all those experienced skydivers, please forgive the extensive ‘Skydiving 1.01’ explanation included for the benefit of us non-parachutists!

If all drop-zone aircraft climbed at the same rate, all parachutists were dropped at the same height and location, fell at the same speed, opened at the same height, descended under canopy at the same speed and no one moved horizontally (apart from wind drift), then the job of a DZC would be relatively simple and there would be virtually no risk of a free-faller from one aircraft meeting an open canopy from a previous aircraft load. The reality is so different. It is also important to note that the DZC is not in fact a controller but an advisor; they cannot give a clearance to drop per se, although jumpmasters would not release their skydivers without the DZC having given the “clear drop” call. Avoidance of each other is a collaborative endeavour between the DZC, those in the air, and the jumpmaster in the aircraft; with the skydivers themselves bearing most responsibility for avoiding others. All that the DZC can do is offer their opinion that there appears to be clear airspace to drop within.

Most commercial parachute centres in the UK use aircraft carrying 15-20 skydivers dropping from between FL120 and FL150. Most skydivers will be dropped individually or in groups on a single pass over the DZ, with the aircraft covering a distance of well over a mile between the first jumper or group leaving the aircraft and the last jumper or group exiting. Most parachutists aim to have their parachutes fully open between 2500ft and 5500ft above DZ level. Once parachutes are open, smaller highly-loaded canopies may descend at over 2000ft/min, while larger or lightly-loaded canopies may descend as slowly as 600ft/min, or even go back up a bit on thermally days. Whilst some canopies will be on the ground within 1.5mins of opening, others may take over 6mins. As a result, canopies from just one aircraft may spread out horizontally over a few square miles of sky, at a range of heights, and with a range of canopy sizes that make it difficult for a DZC to accurately assess height, let alone determine the exact time to descend below 2000ft.  Canopies up-sun of the DZC or transiently behind small clouds add to the difficulty.

Wing-suited skydivers can descend relatively slowly (they may have fall rates as low as a third of normal freefall speeds), and can glide relatively large distances away from and back into the DZ area such that they might come into potential conflict with faster falling non-wing-suiters dropping from later aircraft. This means that they are very difficult to track by the DZC, jumpmaster and other skydivers, compounded by the fact that all this is done visually whilst trying to maintain contact with potentially quite small parachute canopies that can give an illusion of being at different heights depending on the size of canopies.

Even with this complexity, an experienced DZC can usually make a realistic assessment of whether it is advisable for the next load to drop. When this is combined with pilots monitoring each other’s calls and planning at least a 6min separation (and preferably 8min separation), then it is unusual to have significant conflicts. One obvious way to ensure no conflict between loads would be to allow no further dropping until all canopies are on the ground, but this would be commercially costly and very unpopular with skydivers wishing to do as much jumping as possible. Having aircraft hold in the air is not only commercially costly and unpopular but sometimes introduces other safety concerns, particularly concerns about hypoxia when the aircraft is on hold at over FL100. Skydivers are allowed 30mins above FL100 without supplementary oxygen, but only 6mins above FL120 before the drop has to be aborted. Although it is not too bad in summer, hypothermia is also a significant factor in some jump-aircraft if kept on hold during colder months of the year.

A jumpmaster in an aircraft can look down for other canopies before starting to jump and can request a “go around” if they suspect a conflict. However, from 3 miles up at FL150 it is difficult even to see a canopy, and quite impossible to decide at what height it is. In freefall, the most immediate risk of collisions comes from other skydivers jumping from the same aircraft, and it is appropriate that attention is focussed mainly on this area. In the 10-15secs before opening their parachutes, many experienced jumpers will be on the lookout for open parachutes nearby (whether from their own aircraft or from another) but many jumpers will not yet have developed the skill or situational awareness to allow them to do this.

It is easy for jumpers leaving an aircraft to assume that a “clear drop” from DZ control means there is no possibility of a conflict. Careful consideration of timing makes it clear that this is not the case. When a pilot calls “two minutes to drop” and receives the “clear drop”, the “two minutes” is a rough estimate rather than a promise, and the “clear drop” simply means “no obvious conflict seen at present”.  After the first jumper begins to climb out of the aircraft door, it is not unusual for a further 60-70secs to elapse before the last group or individual leaves the aircraft. There is then up to 75secs of freefall time before the last canopy is deploying.  Thus almost 5mins can elapse between the “clear drop” and the last canopy deploying. That is enough time for an already open canopy to travel horizontally across 1-1.5 miles of sky. The “2min” call could be reduced to “1min” or “30secs” in order to slightly reduce the large interval but this may produce chaos in other ways due to busy radio frequencies and failure to obtain a response in time.

It is interesting, and perhaps significant, that although this organisation has a safety management system and a safety committee, and had clearly already given this topic considerable thought, the verbal report of the skydiver to the Chief Instructor did not find its way into the SMS and it was the report to CHIRP that brought it to their official attention. The DZ company SMS should have logged the incident and so it’s not clear why the company had no record of the incident being reported. A SMS cannot review the efficacy of its SOPs if it does not reliably gather data on near misses as well as the rarer major incidents. Is there a clearly visible supply of “near miss” or “concern” forms and pens at manifest, DZ control, packing area and reception so that it is easy for any jumper to make a report to them as soon as they walk back from their jump? On that busy day, perhaps the DZC was too occupied with other immediate concerns to get all the appropriate information (including from pilots and the wing-suiter) and feed it into the SMS. At the time of the initial verbal report it may have been possible to identify the closest free-faller and the wing-suiter and then to confirm opening heights (often logged electronically), opening locations (on POV videos) and post-opening navigation. This would have allowed for a more informative debrief and safety committee discussion. However, it would have required significant time from a senior member of the management team on what was already one of their busiest days of the year.

There is an education piece for wing-suiters to highlight that they should not fly through the DZ stack due to the risk of collision, and the DZ operator might need to think more about wing-suit procedures to allow for their increased drop time.  Additionally, skydivers who usually frequent a DZ with only one aircraft may never have considered the possibility of conflict with another aircraft and may need very specific briefing when visiting a multi-plane operation. Organisations with a multi-plane operation may need to add specific information or cautions to their DZ Briefing for visiting licenced jumpers. It is very easy to assume that “everyone knows”.

Jump composition can be available to DZC and to the pilot flying them (noted on the aircraft manifest) but may not be available to pilots on the following load. It is not known if the DZC was actively aware of wing-suiters being present on the affected load. Likewise, it is not known if distraction could also have played a part for the DZC on this occasion. At some DZs, the DZ control is isolated from other activities, while at others it is in the middle of the throng of jumpers preparing for the next load; this throng inevitably provides distractions (but also sometimes increases awareness of what will happen on that next load).

Communication between jump aircraft about wing-suiters/high openers may also have been a factor. It may be possible to highlight wing-suiters on the pilot’s copy of the manifest so that it becomes standard practice for the pilot to pass this information to following pilots when calling “drop complete”.  This would allow the following aircraft perhaps to plan a longer interval.

Finally, the “big sky principal” means that, even under non-ideal conditions, collisions or even near misses are infrequent; this can lead to complacency and, occasionally, normalisation of deviance by DZCs, management systems, pilots and ordinary jumpers alike.  Jumpmasters at multi-aircraft drop zones may wish to remind their jumpers about the possibility of conflict with previous or following loads, and about the DZ’s SOPs which are aimed at reducing this risk.

CHIRP commends the pilot for their altruistic self-critical comments which represent the finest traditions of an honest debrief that will hopefully provide food for thought for others – this report is a fine example of a frank and honest description of an event that we can all learn from. The reporter has covered the main lessons to be learnt themselves, although it’s not clear whether the A/G operator had reported the circuit direction and they missed it or whether they had simply said that the circuit was busy. Either way, as the reporter comments, it would have been better to have routed further from the airfield if possible because aircraft using the airfield would have been operating under the expectation that the ATZ was theirs to use as they needed. That being said, one might hope that the A/G operator would have broadcast to those in the circuit that a formation was transiting the ATZ so that they could also make allowances in their pattern if possible to accommodate the sometimes unwieldy nature of formation routing, especially since the circuit pattern also extended close to the ATZ boundary at the airfield concerned.

We also commend the reporter for actively taking time to consider TEM before the flight. Although they’re pretty hard on themselves for not fully appreciating the threat that the ATZ represented in the conditions at the time, it’s clear that they had at least thought about it and had taken some steps to mitigate the risks. The strength of TEM is that it arms you with pre-planned options so that you not only avoid unnecessary risks where possible but you’re also not overtaken by events when things might start to go wrong, therefore increasing your capacity to act.

This report highlights misunderstandings that might exist about NOTAMs versus restricted areas and TRAs.  Although published by NATS on behalf of the CAA, NOTAMs are compiled by the requestor of the activity. In this particular case, the NOTAM was a navigation hazard warning with no requirement to avoid it although sensible to do so given the activity likely to be conducted within with small models/drones. For their part, those operating drones/UAS within such NOTAM’ed areas still have a duty to avoid collisions with other aircraft and so they must maintain visual contact with their drone/model at all times – all airspace users have a duty to avoid collisions and must give way to aircraft to the right of their own. Given the often small size of drones/models, there is extra importance in drone/UAS operators avoiding aircraft that they see given that their drone/model will likely be very difficult to detect by an aircraft pilot. In short, unless specific arrangements have been made to operate BVLOS[1] (which requires a TRA at present), a model/drone operator is required to maintain lookout (either themselves or by an observer if using FPV[2]) and must keep any model/drone within their line-of-sight.

[1] BVLOS – Beyond Visual Line of Sight.

[2] FPV – First-Person-View, i.e. using heads-down video or virtual reality goggles.

The NOTAM itself was poorly drafted with a number of errors in heights. The upper limit was erroneously described as the surface altitude in one part and 2500ft agl in another (implying a top height of 3200ft amsl). The intended top-height was 1500ft agl (2200ft amsl) and this was corrected in a subsequent issue of the NOTAM. Whilst we’re all prone to mistakes and errors at times, it shows the importance of understanding the NOTAM compilation process and double-checking any entries to make sure they are correct. NATS have produced NOTAM Guidance Material (see also QR code), wherein Paras 3.2 and 3.3 (reproduced below) give an explanation of how to decode NOTAMs. Although many electronic navigation and planning aids do this automatically for users, those compiling NOTAMs need to understand the various entries and what they mean.

Finally, the 3Cs of Caution, Consideration and Courtesy to others should be our watchwords in aviation. There’s nothing to be gained from being rude or obstructive when people query or ask for further information about a NOTAM, a confrontational tone only causes stress and distraction to others.

NATS NOTAM Guidance Material referred to in this report

3.2 NOTAM Format

NOTAM are required to conform to an explicit template. Using the example below, an explanation of the format follows:

• A1234/14 NOTAMN
• Q) EGTT/QMRLC/IV/NBO/A/000/999/5129N00028W005
• A) EGLL
• B) 1408231500
• C) 1409310500
• D) 1500-1600, 0430-0500
• E) RWY 09R/27L CLOSED DUE WIP

3.3 The NOTAM Construct:

A1234/13 represents the NOTAM Series, followed by a sequential 4-digit number, followed by two digits to indicate the year. (Max 9999/YY).

NOTAMN Indicates this is a new NOTAM. Other options are R for NOTAM replacing another or C for one cancelling another. Replacement NOTAM can only be used to replace a NOTAM that is already in effect.

Q) EGTT/QMRLC/IV/NBO/A/000/999/5129N00028W005

The Qualifying line, or Q Line, is an AIS tool used to categorise the NOTAM according to its scope. It consists of up to eight fields separated by a stroke (/) comprising FIR, Q Code, Traffic, Purpose, Scope, Vertical Limits, Co-ordinates and Radius.

EGTT is an ICAO code, identifying the (London) FIR to which the NOTAM refers. Should the activity take place in more than one FIR then the code EGXX is applied and the specific FIRS affected are inserted into field A of the NOTAM

QMRLC is a 5 letter NOTAM code identifying subject and status. In this case MR is a Runway, LC indicates a closed status. IVindicates that this information is significant for both IFR and VFR operations while NBO indicates a message for immediate attention, for inclusion in a PIB and operationally significant.

A represents the scope which in this case is an Aerodrome NOTAM as opposed to an EnRoute E NOTAM or Navigation Warning W. Combinations AE and AW can also be applied according to the subject being described.

000/999 represents the lower and upper limits expressed as a flight level. In this case it is left as a default as it is not applicable.

5129N00028W005 is the ‘Centre point’ using degrees and minutes followed by a radius of influence. In this case the default value of 5NM has been applied based on the aerodrome ARP. A default radius of 999 is applied for NOTAM that cannot be associated to a specific area and for those that affect the whole FIR.

Position (Where)

A) EGLL is the ICAO code of the aerodrome (Heathrow). While it is possible to insert more than one FIR into this field, it is only possible to enter one Aerodrome. This means that separate NOTAM are required if the impact is on two or more aerodromes.

Effective from (Begins)

B) 1408231500 is the Date/time group in UTC when the NOTAM becomes effective. Year, Month, Day, Time. NOTAM used to replace or cancel other NOTAM can only be issued With Immediate Effect (WIE) and cannot have a future effective (start) date.

Effective until (Finishes)

C) 1409310500 is the Date/time group in UTC when the NOTAM ceases to be effective. Temporary NOTAM shall exist no longer than 90 days.

Where an expiry date/time can only be estimated EST may be included in Field C for temporary NOTAM. Sponsors shall take action to cancel or replace the NOTAM before the EST expiry time.

Planned Schedule (Optional)

D) 1500-1630, 0430-0500 this provides the opportunity to describe a schedule of events within the effective date of the NOTAM. This is particularly useful for events that take place over a period of days or weeks. Irregular schedules that do not meet certain criteria will have to be described in the plain language part of the NOTAM

Plain Language (Free-text)

E) RWY 09R/27L CLOSED DUE WIP is the textual part of the NOTAM indicating that Runway 09/27 is closed due to work in progress.

This item describes the ‘subject’ and ‘condition’ and is probably the most important part of the message. The information should be explicit giving the reader the ability to quickly assess the impact to their operation.

Start with a ‘headline’ to describe the subject and event e.g. RWY…CLOSED, TWY… WIP, DANGER AREA … ACTIVATED, FREQUENCY … U/S. After which supplemental information may be considered to describe the impact.

Avoid information that may be considered as ‘nice to have’ or complementary. Use internationally recognised abbreviations (as per ICAO Doc 8400) unless their use creates misunderstanding. A list of abbreviations is available in the General (GEN) section of the AIP but note that National abbreviations (in italics) cannot be used for NOTAM.

Use of Coordinates

If there is a requirement to describe an area or polygon, the provision of coordinates Degrees/Minutes/Seconds shall be used e.g. 521049N 0012035W. When describing an area repeat the first coordinate in full to close the polygon.

Supplementary Information

The judgment needed to assess the extent of information required in a NOTAM can be problematical. Too much information can serve to overwhelm the reader, whereas not enough information will fail to provide them with an opportunity to assess the impact on the operation.

Guidance in composing the text of a NOTAM can be obtained by contacting the NOTAM Office directly to establish that the proposal clearly captures the objective.

Vertical Parameters

F) & G) describe lower and upper limits. They are not used for Aerodrome NOTAM scoped A; however, they are used for airspace notifications such as navigation warnings, airspace reservations and Danger Area activities. The sponsor should ensure that appropriate values are included in the NOTAM proposal e.g. FL090, 3000FT AMSL.

When the values in Fields F and G are expressed as a flight level (FL) or altitude (AMSL) the associated FL values will also be applied in the Q Line. It is recommended that the use of AGL is avoided in fields F & G, as it demands a calculation based upon the highest terrain elevation for the region or FIR.