So sorry for the kids that have now lost both parents at such a young age. Life can feel hopeless with such a loss, but there can be great joy in the future by surviving and persevering through such devastating losses. Life is less about what happens to us than it is about overcoming, whatever our challenges may be.
Yeah strokes and embolisms can happen from deep vein thrombosis dislodging in higher altitudes. Those with past heart problems should avoid flying as much as possible.