I have an iPad and I think I have downloaded every affordable app!
I don't use mine for nav as I am awaiting for a gos attachment. I also haven't subscribed to any services, so I am currently not using SkyDemon, Aware, aware runway HD or Pooleys. I use mine for planning and it is brilliant, not only does it save time but it gives me a better understanding of the airspace I will fly through.
When I finally get the GPS module, I will still use it as a kneeboard but use a nav app as a back up or for a co-pilot to monitor. I will still use my Garmin 496 which is mounted on my side of the instrument panel and is linked to my comms setup.
I have airnav on my iPhone which can used to tell you where you are if you get an GPS failure. I would recommend this redundancy to anyone. And for the relics, I mainly nav using DR and a chart and I use the GPS to confirm my position. I am not reliant on it and can do without GPS (I practice without regularly) but having a GPS and back-up GPS (iPhone or iPad) means I spend a lot less time staring at the ground and the chart and much more time looking for other aircarft and gaining situational awareness!!!
Anyway, of all the apps I use, this are my recommends.
Weather
WeatherProHD- my main weather app, this has a good forecast and is generally very accurate!
Aeroweather - this is a great METAR and TAF app with built in decoder. The only disadvantage is doesn't have a map function and so you need to search by airport name.
Aeroplusweather - Like aeroweather but not quite as good. It is good for checking METARs along a route as it uses a map function, but it has less stations than aeroweather and you have to subscribe and pay to receive TAF info, still useful though.
Airports
Airfield Cards - a must for the GA pilot, it lists many of the smaller airfields and farmstrips that other apps lack! It doesn't show a airfield chart but describes the circuit pattern and any relevant warnings. A great advantage is that it doesn't use the internet and so you can find the info anywhere. It has a could of buttons on the bottom each airfield card, click one to call through to the airfield for PPR (no more searching for and writing down the numbers) another button to take you to the airfields website (Internet connection required) and another one to bring the airfield up on you map add in aerial photography (makes finding the airfield a lot easier once in the overhead)
Circle to Land - A must for the commercial or IR pilot. It has the airfield cards for most of the worlds airports and includes Instrument Approach cards. This app also has the cards for a lot of the smaller airfields are the UK. It has the option to print any airfield chart or AIP! This app runs off of a saved database and so does not need an internet connection! I think this app was £2.99
Airports - this sits between the two apps mentioned above. Like circle to land it has all of the larger airfields and airports but lacks some of the smaller airfields and farmstrips that can be found in Airfield Cards. Airports has a couple a features that makes it stand out and would make it a great tool for someone that flys regularly and flys all over the UK. The first feature is the Met reports function, you find the METAR or TAF for you nearest main airport. The second feature is the ability to add your own notes for each airfield, you can collate info from other sources or insert info from you own experience as a reminded such as, "beware of E winds - rotors off of hangars". It also uses aerial photography (needs Internet connection) or a very simplied runway layout. This app is great for planning alternatives as it lists them by distance and direction.
Fore flight - I don't really use this as I prefer Aiports, as fore flight doesn't aerial photography and is designed for use the in the US and Canada. One useful feature it does have is wind aloft readings for the larger airfields and airports with METAR/TAF info. This app is not a must though if only operating in the UK
These three are great tools and I tend to use all three. If conducting a lot of IFR flight, you will use circle to land complimented by airports, if you fly local VFR and like I do you will use these as I do:
I use Airfields as a quick check to check runway direction and circuit instructions, I then use this app to call for PPR and then use the app to have a quick look at the aerial photography. Once happy, I go on to airports, have a more detailed look at the aerial photography, check the local Met, check my own notes on the airfield and finally check to see if there are any NOTAMs on the airfield. With all the info taken from these apps and put onto my kneeboard, I am good to go. I am flying into a larger airfield (licenced), I will use circle to land instead of airfield cards and I can even print out the airfield charts. I will then use airports to check Met, notams, my own notes and use the aerial photography to write notes of how to find it.
RouteRocket now have an app called aeroplates which is very much like circle to land but in my opinion is not as good as it doesn't have a map function.
Flight Planning
SkyDemon Light - IMHO, quite simply the best flying app out there. It is simple to use, uses a digital uk chart, you can vey easily plan a flight, insert details of your IAS, the weather and it will create a flight plan for you displayed as it would on you kneeboard!!! You can also enter you altitude for the cruise and it will tell you all the NOTAMS you go through or near, this mean you can simply vary your altitude to find the alt that best suits the weather and minimises the NOTAMs. All the NOTAMs are displayed on the map and can be interrogated by simply tapping on them. This is surprising useful for me as I fly near Lincoln and so I can see the planned route for the red arrows and BBMF with timings. Once an altitude is entered, it warns you of any aerial obstacles or restricted airspace en route, simply click on the warning to be taken to the airspace on the chart and plan a route around. You can use to find airfield and vor freqs. If that wasn't enough, once you have finished your flight plan, checked the NOTAMs and airspace warnings applicable to you route, simply tap on the file flight plan button, fill in the necessary details and file your flight plan. I cannot sell this app enough. It doesn't require an Internet connection to use the digital chart or check airspace warnings, it only needs an Internet connection for NOTAMs and flight plan filing. It will store NOTAMs so you can use it with an Internet connection in the morning and use the mornings NOTAMs later that day if needed. Best thing though, there is no subscription.
Notams (the one with a pic of a helicopter on the front) - my favourite NOTAM app which I used to always use, still great for iPhone!! It uses a map to display all NOTAMS up to 5000ft and so it can be very easy to find the info. I don't use it much now as all the same features are on SkyDemon Light and SkyDemon actually shows how the NOTAMs affect the airspace. I will now only use this app on my iPhone if I don't have my iPad with me. This is a free app.
Pilot Wizz - IMHO better than flight plan. It is an IPhone App but is great for flight calc such as headings,mground speed, density altitude etc. It is a convertor and has a holding pattern aid function and TAF decoder! A must for the IPhone and great for the IPad.
xWind - a great iPhone app that quickly calculates your crosswind component. Pilot Wizz can also be used for xWinds but I just like this app.
Route Rocket Flight Filer - this is a flight plan filing app which imdon't use as SkyDeon has the same feature but I have heard very good things about this app.
During Flight Apps -
I don't currently use my IPad as a gps and so i will not comment on those. Instead I do sometimes use the follow IPhone apps on my iPhone and not on my iPad.
Flight timer. This app is great, I don't have a clock in my aircraft and this app allows me to run two clocks at the same time, one for flight time and one for leg time.
Checklist Lite, this free IPhone app is great for creating you own checklists. It displays each check one at a time and you you click to say complete or not. Fit stores the checks and so you can go back and see which checks you couldn't complete. By far the best function though is the emergency checklist button which is always on the screen. Tap on the button and it takes you through to a whole new sets of checklists which you can create. I have a checklist for all possible emergencies. I wouldn't rely on it but its a great tool for checking you have taken the correct action once you get a chance to think or troubleshoot.
Good reference apps
I also keep a library of aviation reference on my iPad so if I need to check the theory on something, I can.
FAA Theorectical Knowldge. The FAA have put thief theoretical knowledge handbook onto the IPad and it is currently free. This is great app but needs to be taken with a pinch of salt as some info contained will not be applicable to UK airspace or the the CAA's air law.
Red Circle Apps - Red Circle have created mock exam apps for each area of the ppl syllabus. If I am bored, I complete some of this tests now and again to make sure my knowledge is up to scratch.
The above are my recommended apps for iPad and IPhone and as mention, I use my IPad as a planning tool and my iPhine as an aid to navigation and back-up GPS (not needed so far), and this works for me.
To finish off this incredibly long post, I will list the order in which I use the apps when flight planning:
1. WeatherProHD - general forecast
2. AeroWeather - TAFs and METAR
3. SkyDemon Light - flight planning and notams' copied flight plan onto chart and kneeboard
4. Airfield Cards or Circle to land - depending on airfield size and type- call for PPR
5. Airports - check aircield TAF, alternates, aerial photography and check my own notes
6. XWind - Check x wind component
7. Pilot Wizz - convert any units reqd, calc alt density and TAS etc. I alway like to know the altitude at which the OAT is the dew point.
DISCLAIMER: The opinions expressed here are just that my opinions and based on my own experience, they should not be taken as consumer advice or advertisement.
I hope this helps.