Drone Inspections – Lessons from Practice

I officially started my drone inspection business in March 2019 – which is when I registered the business – although I had spent the previous year practicing flying drones, and taking the courses which would lead me to the required qualifications to operate drones commercially.

At that time there was a distinction between ‘commercial’ flights and ‘recreational’ flights, a distinction which has now been removed from CAA regulations – along with numerous other changes to the rules.

While working continuously and trying to keep abreast of the CAA regulatory ‘muddy waters’ over time, there are a number of lessons and useful tips I have learned which are the sort of things that formal drone training courses don’t teach you.

The everyday things that happen while flying drones for work, or drone-flying situations which are not part of formal courses, but which are useful for less experienced drone pilots.

So here, in no particular order as they say on reality TV shows, are my top tips for surveyors working with drones.

Wind.

Weather is a massive consideration for flying drones.  Rain is a definite No-No for the types of drones most building surveyors will be flying. Water in the electronics would be an issue – and the most common drones are not water-tight.

Bright sunlight casts dark shadows over roof pitches, obscuring important details, as well as blinding the drone operator when looking up towards the sun.

And ice, frost and snow are an issue, not only to the working of the drone (ice can form on rotor blades in freezing conditions), but also that roofs covered in frozen white stuff are not visible for inspection.

Wind is a deceptive issue all on its own, and could be the subject of a separate blog article by itself. Various weather forecasts will predict a general wind-speed for a site, and  give figures for gusts.  The gust speeds are the key figures to take notice of.  Different drones have different wind-resistance capacities, but I personally tend to restrict flying to gust speeds of less than 30mph.

However, even the gust speeds can be deceptive. Wind action around and over buildings and structures is very unpredictable. Gusts can be magnified in narrow spaces between structures, but reduced to nothing on certain sides of a building.

When flying low over pitched roofs, a positive pressure on the wind-ward slope can cause the drone to rise unexpectedly, while on the lee-ward side, negative pressure can draw the drone downwards alarmingly.

The lesson – if flying close to buildings or structures for inspection, is to be aware of the general wind speed and direction. Anticipate the danger areas according to the shape of the building, location of the drone, and direction of the wind.  If in doubt, don’t fly.

Birds

The majority of birds are no problem for drone flyers.  But gulls and pigeons present real dangers to drones.

Gulls have a bad reputation for stealing chips and ice-creams out of peoples’ hands, but they are fiercely protective of their nests and will attack drones which they see as a threat, and the level of their protectiveness will be in direct proportion to the distance of the drone from the nest.

Pigeons, on the other hand, are less malicious but will flock around at the sound and presence of a drone, flying around the drone in circles, and possibly colliding with it if they are allowed to fly too close.

Where gulls are concerned, the nesting season of April to September, is the critical time when gulls are most aggressive towards drones.

So when carrying out drone roof surveys, the trick is to try and locate the positions of the nests and keep drones at a suitable distance. The gulls let us know what that distance is.

Pigeons will flock in circles, but often the drone can be flown at a height above the circuit of the birds, and very often they will get used to the presence of the drone and retire to their previous hideaway.

Drones with good optical telephoto lenses come into their own for this type of work – machines such as the Mavic 3 Pro with its 168mm lens can obtain detailed imagery from distances which don’t upset the birds (too much).

Apart from gulls and pigeons, buzzards and red kites can be a threat to drones, although I have not experienced this yet.  I have had buzzards keep a watchful eye on my drones, but never more than that. However there are reports of drone operators having issues with these predatory birds.

One final point about birds – Peregrine falcons often inhabit the higher parts of buildings, such as towers or recessed nooks and crannies. These birds are protected, as are all birds, but due to their status as a “Schedule 1” species, falcons have additional protection.  Drones should be kept away from them when their presence has been identified.

Pre-plan

We are not free to fly drones in all locations.

Flight Restriction Zones (FRZ) exist around a number of facilities.  Airports are commonly known to be restricted, but so are prisons, nuclear establishments, and a host of military sites.

It is a criminal offence to fly drones in these restriction zones without approval from the relevant authorities.

Sites such as ‘The Dronemap’ (https://thedronemap.com/)and ‘NATS’ (https://nats-uk.ead-it.com/cms-nats/opencms/en/uas-restriction-zones/) provide good information about restriction zones, and should always be checked prior to launching a drone.  It’s surprising how often a restricted area pops up in a proposed drone survey.

Different methods of seeking approval for drone flights in restricted areas apply.  For airports and aerodromes, look-up the relevant airport’s website in relation to drone flying – most have an instruction on how to obtain approval.  Some airports apply charges for approval, paid via a third-party agency acting on their behalf.  Sums of £15-30 are common fees. A select list of major airports, such as Heathrow and Manchester, do not charge but a formal application must be made via NATS.

Prisons and nuclear power stations are more tricky to obtain permissions from, but applications can be made via AROps AROps@caa.co.uk  Allow 28 days for approval.

Neighbours

While you may have approval from your clients to fly a drone around their property, people in adjacent or nearby buildings are likely to be concerned at the sight of a drone near their windows.  You can be sure that these people will assume that the drone is looking their way.

Good and courteous practice, is to speak to any neighbours before flying the drone, advising them of your intention to fly, the reason for the flights, and assuring them that only your client’s property will be the subject of your photography.

Some people will actually ask you to take a look at their roof while you’re there.

Neighbours refers to any property which is within the flight area of the drone.  These will include;

·       Houses – residential (next door neighbours)

·       Industrial buildings (there’s always another business nearby with concerns)

·       Schools (particularly sensitive due to the need to ‘safeguard’ children.  Safeguarding includes leaving no possibility of photographing the students – sometimes even through classroom windows)

·       Nurseries (it’s surprising how often there is a day nursery nearby)

·       Police stations  (watch out for the ‘drone auditors’  – best not to be associated with them)

·       Anything Government (their offices are everywhere)

·       Town centre offices (past experience has revealed the presence of HMRC, Customs & excise, and Counter-terrorism departments in anonymous office buildings)

·       …..and others

Guilty till proven not

As a follow-on to the ‘neighbours’ warning, drone operators should be prepared for the assumption that they are up to some type of nefarious activity.

If operating around a unit on an industrial estate, occupants of adjacent units may be alarmed, and will commonly assume that the drone is being used to look for plant and equipment worth stealing, or means of access for purposes of theft, while neighbours of residential property will often assume that the drone is being used for voyeuristic purposes.

As described earlier, it is good practice to speak to anyone who might be concerned prior to launching the drone, and always keep business cards and any useful documentation with you.

Security guards

They never get the email.

Many commercial, industrial or hospital sites have security guards – either sitting in a gatehouse, patrolling the grounds, or on-call response units responding to alarm systems.

These people always sit up and take notice of a drone invading their air-space, and ideally will have been notified of the intended drone inspection. However, there is always a chain of parties involved in arranging access and permission for the drone to fly around the property, and no matter how many emails are exchanged in making these arrangements – the people at the bottom of the chain, the security personnel on site – rarely receive the message.

Anyone carrying out aerial surveys of roofs or buildings with a drone on property which is attended by security personnel should, on arrival at the site, expect to have to explain themselves to the staff, who may initially be confused about the suggestion of a drone flight.

Being able to present relevant documentation, names and contact details of any managers involved, and specific instructions often ameliorates the process of access to site – along with branded hi-vis and official-looking identity cards.

Never expect the front-of-house security people to know you are coming.

(I appreciate that poor communication to the people on the ground is an issue generally in business – but the suggestion of a drone being employed always raises the stakes further).

Become invisible – by being visible.

When I started my business, I automatically ordered branded hi-vis vests and jackets.   I did this because I believed this to be standard practice for all professional businesses working outdoors.

I soon discovered however, that while flying my drone – somewhat self-consciously – in public places, that the public were taking no notice of me.

I realised that most people, on seeing someone working in the street wearing hi-vis clothing, assume that they are working there ‘officially’, and subconsciously dis-regard them.

We effectively become invisible by wearing hi-vis clothing. Don’t consider your hi-vis clothing to be equivalent to an ‘invisibility-cloak’ though, as there will still be passersby who recognise that a drone-flight is being conducted and will simply enquire about its purpose. However, the simple explanation of ‘roof inspection’ is usually sufficient to send the enquirer happily on their way.

One down-side, is that if working in public streets, or anywhere associated with car parking, you will often be assumed to be a car parking attendant.  Be ready to field questions about local parking places, ticket machines, and parking fees.

Branded hi-vis answers many questions before they are even asked.

Always look up.

There’s lot’s of useful advice on-line – on the CAA website – on various drone forums – on You-Tube, etc – mostly centred around drone rules & regulations, and resources to check that you will be flying legally and safely.

All good stuff.

But my own piece of advice, based on much real-world experience, is – always look up.

Before you launch any drone, anywhere, look up.

It’s surprising how often there’s an overhead phone cable, or overhanging tree branch, or electricity cables directly above the drone, which wasn’t noticed with eyes focused on the drone on the ground, and the pressure to get on to the next job.

Always look up.

Public questions – and dogs

Once you have been spotted flying your drone, you will probably with faced with some standard common questions;

How far does it go?

How high can it fly?

What does it cost?

…..and the regular – have you been flying it in Ukraine/Russia/Iran (delete as appropriate)?

Most passersby will do so with little recognition of your activities, however if they are walking a dog, the hound may be interested in your kit, and given an opportunity, might want to leave their scent on it.

Most commodity drones are not water-resistant – either to rain-water or dog-piddle – but it’s best to not let the situation arise and move your drone out of the way of the approaching canine before an awkward situation arises.

Helicopters.

Awareness of helicopters is normally covered in drone training courses, to a greater or lesser degree according to the particular course.

But there is no amount of course training that can prepare you for the approach of a helicopter into your little bit of air-space.

Helicopters are the biggest aerial risk you will face while flying a drone.

Firstly – there are more helicopters in the sky than you realise until you fly a drone.  Police, Air-ambulance, Coast-guard, Military and civilian choppers are regularly present over our towns and cities, as well rural locations.

In theory, their movements are controlled by local air-traffic control. In practice, I have found that they are a law unto themselves. They can fly at any height above ground.  Their routes are not generally restricted, and their approach is alarmingly fast.

There is little you can do about helicopter incursions other than be alert, spot their presence and path, and lower the drone as low as possible out of the way – preferably land it. The rule of the sky is ‘see-and-avoid’, but it is incumbent on the drone operator to avoid – for obvious reasons.

The best precautions is to understand the locality of your drone flight.  If near a hospital, there may well be an air-ambulance helipad on the hospital site.  Expect the arrival of one (I once had two air-ambulance arrivals in one day while carrying out roof surveys on a hospital estate).  Military bases are another obvious location for helicopter arrivals, although new drone restriction zones have come into force regarding military sites.

But civilian helicopters are ever-present in all places, so – like Radar O’Reilly in MASH – just be alert to the sound of choppers.