Dealing with inclement weather Q&As

One of the most frustrating aspects of air travel is a delay caused by inclement weather, in particular fog. The frustration of passengers is shared by airports, airlines and its ground handlers. After all, it is their job to keep people moving and when things prevent this then it has an impact on operations.

 

Why does fog prevent an aircraft from landing?

Being a coastal airport Jersey is, on occasions susceptible to foggy conditions, which can occur with little warning, even with the excellent services provided by the local Met Office. When this happens aircraft are unable to see the runway and must rely upon instruments on the ground and in the cockpit to land the aircraft safely.

 

Why do some aircraft ‘go around’ instead of landing?

This is related to the density of the fog. Even when it is foggy the aircraft captain, with the assistance of his onboard instruments is able to accurately position onto final approach, although he must be able to see the approach lights before committing to land. If the captain does not see the approach lights by a certain height, which in Jersey for a Category 1 Instrument Landing System (ILS) is in the region of 200 feet, then the aircraft must perform a ‘go around’, which means it climbs away.

 

Is there anything else that needs to be taken into consideration when attempting to land?

As well as the decision height, there are minimum horizontal visibility limits that must be present before the aircraft is allowed to commence its approach. This minimum visibility is dependent on how many approach lights are installed on the airfield and their effectiveness. Jersey Airport has good approach lights on runway 27 (landing over the Island in an east to west direction). For runway 09 (landing over the sea from west to east) the airport is restricted by the location of the runway and only have a limited number of lights at this end before reaching the edge of the cliff.

 

Jersey Airport has a Category 1 ILS – what does this mean?

In aviation there are different categories of instrument landing systems. Each category determines a decision height (the height at which the captain has to decide whether to land or go around) and a minimum horizontal visibility. Depending on the runway lights and approach lights this varies. For example, on runway 26 at Jersey Airport the minimum horizontal visibility is 550 metres; which is the lowest you can have with a category 1 ILS and for runway 08; due to the limited approach lights the minimum horizontal visibility is 1000 metres.

 

So why can’t Jersey Airport have an ILS with even lower limits?

Unfortunately, this is down to geographical features and the obstacles around the airfield. The next category of ILS is a 2, which would allow aircraft to land in much denser foggy conditions. However, for Jersey Airport to achieve this there are some crucial limitations that would have to be addressed first. For example:

When using a category 2 ILS the aircraft must be fitted with a radio altimeter. This is a piece of safety equipment that tells the aircraft crew very accurately how high the aircraft is above the ground. The altimeter must be within certain parameters in the final stages of approach to land and the larger changes in this reading due to St Peter’s Valley and the cliff above St Ouen’s Bay render it unusable for a category 2 ILS.

Aircraft crew trust the safety of the aircraft and the people onboard to the equipment and protection of the surrounding areas. This is known as the ‘obstacle free zone’ and allows for margins of error, equipment failure and unexpected situations. This essentially means that the closer an aircraft is to the runway the more protection must be taken regarding objects that are protruding in the sky. St Peter’s Church is an example of such an immoveable object.

 

So, it is likely that Jersey Airport can never have a category 2 ILS?

Never say never. However, it would require a substantial amount of financial investment and local disruption in changing the surrounding environment and removing obstacles to comply with the increased safety requirements that come with a different type of ILS category. Additional and significant investment in improved runway and approach lights would also be required. Therefore, at present there are no plans to change the category.

 

Is there anything else that can be done?

With new technologies there are improvements and enhancements that can be made to complement category 1 ILS approaches. This technology is called ‘Lower than standard Category 1’ and utilises additional equipment onboard the aircraft such as Head Up Displays and Enhanced Vision Systems. This is available today for aircraft such as the Embraer 195 type, hat have it installed and aircrew who are correctly trained. The use of this procedure will undoubtedly increase as more airlines become equipped to allow them to fly these approaches.

 

Why is it easier for aircraft to depart in foggy weather than it is to land?

Arriving aircraft are reliant on ILS while aircraft departing from Jersey are not. However, it must be remembered that although aircraft may be able to depart Jersey in bad weather it must equally be safe for it to land at its destination airport as the same restrictions may apply.

 

Would it not be easier to relocate Jersey Airport in another part of the Island?

Not really. Mention has been made of relocating the airport to the east of the Island but as stated previously Jersey is susceptible to inclement weather regardless of the location of the airport. Add to that the enormous costs involved in relocating an airport of this size, coupled with the major disruption to island life and nearby residents, etc. it is safe to say that in these current times this is not an option.

 

When there is inclement weather and an obvious delay why do airlines insist passengers check-in on time and remain within the terminal building?

All arrival times of aircraft delayed by fog are approximate and in particular, aircraft ‘holding’ can land at very short notice and require a quick turn-around to depart. Therefore, in order to accommodate this dynamic operation airlines and their ground handling agents require departing passengers to remain in the terminal so that they may be called at short notice to depart. 

 

Why must departing passengers return purchased Duty Free goods when a flight has been cancelled?

Duty free goods are controlled by customs regulations, which mean that if a passenger does not eventually depart from the country where duty free goods have been purchased they are not entitled to keep them. Furthermore, in some cases of cancellations passengers may choose to depart on a different day and as such will have to clear security again, where bringing large quantities of liquids are not permitted under the current restrictions.

 

If a flight is cancelled, why aren’t passengers automatically booked onto another flight without the need for having to rebook?

Every passenger's needs are different. For example, some may be travelling for a specific event, which as they may be forced to miss would prefer to cancel their entire journey. In addition, passengers travelling for leisure purposes may decide to rebook on a different airline at their own expense or on an alternative day. Furthermore, there are often occasions when the next available flight does not have sufficient seats to accommodate all passengers affected by a cancelled flight. Passengers with onward connections with the same airline will usually be given priority rebooking.

 

Why do some airlines compensate some passengers in times of delays and cancelled flights such as food and refreshment vouchers, while it appears some airlines do not?

Although all EU airlines are bound by a compensation scheme airlines implement the policy in different ways. Therefore, the general advice for passengers who may have concerns is to check the individual airline policy before booking.

 

Download an overview of Instrument Landing Systems (ILS) at Jersey Airport (size 689kb) 
Download ILS Incident 2012 – Investigation Report (size 205kb)