How to read SIDs and STAR charts

SIDs and STARs can require you to fly specific profiles to prevent you from interacting with other aircraft from other airports, and one such way to prevent this interference is to use altitude restrictions, these can come in one of 2 forms.

Hard constraint

A hard constraint is depicted by there being one line above and one line below the altitude to indicate that you should be at the specified altitude by the specified point unless told otherwise by ATC.

Soft constraint

This is where you should either be above or below the specified altitude. If the line is below the altitude then you should be at or above the specified altitude. If the line is above the altitude then you should be at or below the specified altitude.

Altitude restrictions on SIDs and STARs may be ignored if the controller issues a separate instruction. For example, if you are departing and London says “climb FL100” then you do not need to follow the SID profile, and instead, climb to FL100 immediately.

Sometimes SIDs and STARs require a specific speed to fly, for example, if they are flying a sharp turn on departure that goes against the normal rules (for example speed of 250 knots bellow FL100 in the UK) then these will be specified on the chart at the points where the speed restriction applies.

In the example above, before reaching the waypoint KKE09, there is a maximum speed restriction of 220 knots to prevent overflying the turn and interference with Heathrow departures. However, as with everything, this speed restriction is deemed invalid if ATC says otherwise. Additional speed restrictions may be found in the notes section of the chart

The transition altitude is the minimum altitude in which ATC utilizes the local QNH. This is important as it lets you know at what altitude to select the standard QNH of 1013. The Area Mnm Alt is the minimum safe altitude, meaning that it is the lowest altitude that you can fly at whilst being safe from terrain, this is important because if you have to level off due to something like an engine failure, then you know at what altitude to stop your climb at to be able to return safely to the airport. There is a nice waypoint box to allow you to make sure that the waypoints are defined in your FMC properly and a frequencies list so that you can have an idea on the next frequency to contact and can put it into your coms panel to save time.