# How do I read OOSHN5?

I want to follow the OOSHN5 arrival route, but i have a few questions about it. How do i know what VS to use in between the WPTS? also what are the numbers under the altitudes with the *?

3 Likes

Or this

3 Likes

I believe you are to calculate your own VS and just have to meet the crossing restrictions.

2 Likes

Vertical Speeds are pilots discretion, meaning you can use whatever VS you deem needed to achieve the altitude at the point.

1 Like

The OOSHN5 into KBOS is a â€ścontinuous descent arrivalâ€ť meaning youâ€™ll keep on adjusting down to hit at/between targets. A good way to do this is by using In Flight Assistantâ€™s VNAV feature (comes with the GPWS in app purchase-only on iOS as of now iirc) If you canâ€™t use In Flight Assistant to get your speeds and altitudes setup-you can do some simple math if you have a calculator or other device handy. If youâ€™re between 14000/9000 at OOSHN (letâ€™s say 13000â€™ for the purposes of this) and at 250kt going for 22L (Via GRGIO BRGIT ADDAA LEEZI) and youâ€™ve got 2:30 time to go to GRGIO where you need to be under 9000 youâ€™ll need a VS of -1600 or so to get under 9K at GRGIO. With that in mind, you HAVE to be AT 7000 at BRGIT.

I find that when I need to calculate or input into VNAV-that itâ€™s better to calculate/input the VNAV to the HARD limits-the ones that have two lines above/below them. So say youâ€™re at 13K/250kt at OOSHN-and youâ€™ve got 4:45 time to BRGIT and you need to get down to 7K at BRGIT.
The math on that is 6000/4.75=VS -1263

The IFA VNAV feature is waypoint for waypoint-thereâ€™s currently no â€ślook aheadâ€ť or profile calculation as it were. If youâ€™ve got two waypoints that are setup close to each other and you put an altitude in-the IFA VNAV will tank you down at -5000 max in an attempt to get there.

The OOSHN is a fairly gentle descent profile save the 4.7 mile run from BRGIT to ADDAA where youâ€™ll slow to 220kt and descend 1000â€™ in 4.7nm as youâ€™re slowing.

Iâ€™ll put a video on this up later on today. Iâ€™ve not flown the OOSHN in a while-I mostly use the ROBUC3 and JFUND2 with my VA. Any questions feel free to ask here or in a DM

2 Likes

This topic was automatically closed 90 days after the last reply. New replies are no longer allowed.