The published timetable, and what it is not
The most-searched question about the Mach Loop is when the jets come through, and the honest answer begins with a disappointment. The Ministry of Defence does publish something on GOV.UK called the Operational Low Flying Training Timetable, and a great many visitors find it, assume they have found the schedule, and set off. It is not that. Operational low flying is the deepest tier of low-level training, and the timetable lists only the activation windows for the three Tactical Training Areas where it is permitted: LFA7(T) in central Wales, LFA14(T) in northern Scotland and LFA20(T) on the Anglo-Scottish border. It is published a week at a time, it gives a window such as “11am to midday” against a day, and for central Wales it very often says nothing at all — a sample week we looked at showed no activity for LFA7(T) on any of the five days. The publication also carries its own health warning, that “the MOD is unable to provide a timetable for all low flying activity as the information can very quickly become outdated due to weather conditions and training requirements”.
Why the timetable does not tell you what you want
There is a further twist that catches people out. According to the MOD's notes on the timetable, when a Tactical Training Area is active, operational low flying is being practised at between roughly 100 and 250 feet above the ground — but routine low flying by everyone else is pushed up into the band between 500 and 2,000 feet. When the TTA is not in use, standard low flying training is permitted down to 250 feet, and helicopters down to ground level. Most of the passes that visitors photograph in these valleys are that ordinary 250-foot training, not operational low flying at all — and ordinary low flying is never timetabled, anywhere, by anybody. The MOD's general guidance is equally blunt about routes: “There are no set flight paths. Aircrew plan each sortie individually.” So the one document that looks like a schedule covers the wrong tier of flying, and the tier you are most likely to see has no schedule at all. Anyone who tells you they know what is coming through and when is guessing.
The pattern that does exist
What can be said is that military flying broadly follows a working week. Wikipedia's article on the UK Low Flying System states that flying “is carried out from 0800 to 2300 during weekdays only”, and the long-established enthusiast guide at machloop.co.uk describes the same shape from the ground: a Monday-to-Friday pattern with weekends “typically quiet — not always blank, but significantly less active”, and aircraft usually appearing within RAF working hours of roughly 09:00 to 17:00. That site also notes that UK bank holidays produce almost no activity, that the Christmas and New Year period is effectively dead, and that August can be thin because squadron leave and US federal holidays fall together. None of this is a promise or official, but the direction of travel is consistent: a Tuesday or Wednesday in spring is a better bet than a bank holiday Sunday. If your only free day is a weekend, go anyway and treat any aircraft as a bonus.
Cloud base decides the day
Weather is the other half of the answer, and in these valleys it is usually the deciding half. Crews flying at a few hundred feet through steep-sided ground need to be able to see that ground, so when cloud sits on the ridge lines the route simply is not flown, whatever anyone had planned. machloop.co.uk puts a figure on it — if cloud sits below approximately 1,500 feet in the valleys, aircraft will not fly the route — and while that is an enthusiast's rule of thumb rather than an official minimum, it matches what visitors report. The practical consequence is that you should read a mountain forecast rather than a town one. The Met Office publishes a mountain forecast for Eryri that gives wind, temperature and a percentage “chance of cloud-free hill tops” at 300, 600 and 900 metres, and the Mountain Weather Information Service issues a free Eryri forecast three days ahead under headings including “Cloud on the hills?” and “Chance of cloud free summits?”, quoting cloud base in metres. A high chance of cloud-free tops is the single most encouraging number you can find before setting off. Our Machynlleth weather page covers what the valley does to a forecast more generally.
People drive a long way and see nothing
This needs saying plainly rather than in a footnote. Blank days happen at the Mach Loop in every month of the year, including in the middle of a fine summer week, and the specialist guides say so themselves: machloop.co.uk advises budgeting two days minimum and treating every aircraft “as a bonus rather than a right”, and describes blank days as more common than newcomers expect. Aircraft availability, exercises overseas, a change in the training programme, a serviceability problem or one band of Atlantic cloud will each empty the valleys on their own. If you have driven from the Midlands for the day and the hill is silent, that is not bad luck, it is the normal outcome. The way to enjoy the Loop is to build the day around the walk, the view and the company, and to have a proper plan for the hours when nothing comes — which is what our page on planning a Loop day is for.
Where live information actually lives
We do not track daily activity and we are not going to pretend otherwise. The people who do are the enthusiast community, and they do it well. machloop.co.uk carries location guides, a beginners' guide and news, and is candid that “there is no public timetable”. Its own FAQ describes how watchers work in practice: online tracking through services such as ADS-B Exchange and 360Radar, with the important caveat that many military aircraft do not transmit a trackable signal at all; airband radio scanners on common low-level frequencies; and, most usefully on the day, community groups in which people already standing on the hill post what has just gone through. That last channel is the closest thing to live information that exists. These sources will tell you whether today is worth the drive far better than any page written in advance can. What we can add is the local half: what you might realistically see, what to point at it, and where to get a hot drink afterwards.
Day trips